species embraced are not less than eighty-eight in number, of which only half a dozen have been described. It is the opinion of Professor Hall that all the silúrian formations of New York, previous to the beginning of the geological survey, did not afford more than four or five. Now, about sixty species have been ascertained. Professor Hall mentioned the fact, that all the crinoids of the lower silurian rocks, with the exception of one species, have five pelvic plates, and we never find one with three, or any other number of these plates, before we reach the highest deposits. In Tennessee, the crinoids are so abundant, that Professor Troost states that he had been able to collect some 300 or 400 good specimens of seven or eight different species in a single morning. In relation to the abundance of these fossils in the United States, Professor Agassiz remarked, that it is not, perhaps, sufficiently appreciated of what importance, and of what immense value the study of these fossil crinoids may be for the progress of palæontology. American students should be proud of these materials, by which they will be able to throw so much light upon these almost extinct families by their personal investigations, which will not only render them independent of the palæontologist from abroad for information with regard to the succession of types, and the full illustration of these structures, but really afford correct standards for comparison. It is the more desirable that all these fossils should be made known, as the family of crinoids is so reduced in our days that we can form no idea of the living animals of that group, of their diversity of form, modification of character, and peculiarity of position, from the living type only. He doubted whether the number of crinoid heads of all species found in Europe, now existing in the Museums of Europe, is one-third the number of those which have been found by a single gentleman in Tennessee in one morning. Now, with such materials, consider what precise and what minute investigations could be made. And if these facts could be once fully ascertained and well illustrated, there is no doubt that the series of crinoids, and their succession in former ages, will be established from American standards, and will no longer rest upon the European evidence, which has often been derived from the examination of small fragments of those ancient fossils, found in unconnected basins for the most part, so that their geological succession could be ascertained only with great doubt and difficulty. In conclusion, Professor Agassiz would venture to say, that geologists who have had any opportunity to compare the position of the ancient rocks on this continent of North America with the corresponding deposits of Europe, would agree with him in saying that the geology proper, the stratography of North America, will afford the same precise and well authenticated standards for the appreciation of the order of succession of rocks, as fossils will for the order of succession of living beings.—American Annual of Scientific Discovery, p. 282.

mal on the shores during the paleozoic period. Thirty-one genera, sixteen of which are considered by Professor Troost as new, are enumerated.

11. Discovery of Coral Animals on the Coast of Massachusetts.Professor Agassiz, while on an expedition in one of the vessels of the coast survey during the past summer, obtained by means of a dredge, from a depth of seventy-two feet, in the Vineyard Sound off Gay Head, several specimens of a coral with its animals. By great care and attention they were preserved alive in glass jars for more than six weeks, and afforded an excellent opportunity for an examination and observation of their structure and habits. These corals belong to the genus Astrangia, and have been named by Professor Agassiz, in honour of Professor Dana, geologist of the exploring expedition, Astrangia Dana.

This species presents two varieties. Some are of a pink or rose colour, others are white. The general form of the animal is a cylinder (as of all Polypi) resting on its base, and expanded on the upper margin; thus expanded it is about two lines in diameter. The number of tentacles is definite, but it is not always the same absolute number, It never exceeds twenty-four; in earlier periods of life there are only twelve, and there is even an epoch when there are only six.

It is, perhaps, a matter of surprise that the coral animal should have been found in this latitude. They teem in the warm latitudes; but there are very few species in the more temperate regions, and but for the opportunity afforded by the coast survey, the existence of these animals could not have been suspected on these shores. For many years, however, dead fragments had been found along the shores; but whether they lived there naturally or not had not been ascertained.—American Annual of Scientific Discovery, p. 311.

12. On the Circulation and Digestion of the Lower Animals.Professor Agassiz states, that the circulation of the invertebrata cannot be compared to that of the vertebrata. Instead of the three conditions of chyme, chyle, and blood, which the circulating fluid of the vertebrata undergoes, the blood of that class of the invertebrata which he had particularly studied, the annelida or worms, is simple coloured chyle. The receptacles of chyle in different parts of the body are true lymphatic hearts, like those found in the vertebrata; this kind of circulation is found in the articulata and mollusks, with few exceptions, and in some of the echinoderms. In the medusæ and polyps, instead of chyle, chyme mixed with water is circulated; this circulation is found in some mollusks and intestinal worms. Professor Agassiz thinks, that the embryological development of the higher animals shews a similar succession in the circulating function. As regards the connection between respiration and circulation in vertebrata, the gills are found between branches of the blood system; in invertebrata, the chyliferous system is acted on by the respiration. The gills of fishes, therefore, cannot be compared to the gills of crustacea, articulata, and mollusks. In fact, no gills are connected with

the chymiferous circulation. Animals having this circulation, have no true respiration. They have only tubes to distribute freshly aërated water to different parts of the body.-Proc. Bost. Nat. Hist. Soc.

13. Distribution of the Testaceous Mollusca of Jamaica.—The great number of species is remarkable. A few miles of coast, without the aid of storms, and without dredging, yielded 450 species. In the small bay of Port Royal, 350 marine species were found. A pint of sand, taken from a surface three yards long, contained 110 species. Probably there are 350 or 400 specimens of land shells, and two or three times as many of marine species. Extensive districts occur, however, which are nearly destitute of land or marine shells. They are accumulated in favourable stations.

The difference in the extent of the distribution of the marine and

of the terrestrial species is remarkable. A majority of the marine species are known to occur in the other islands; probably not more than 10 or 15 per cent. of them will be found to be peculiar to Jamaica. But of the land shells, 95 per cent. are peculiar to the island. The limited distribution of the terrestrial species is remarkable. A few are generally distributed, but a large number are limited to districts of a few miles in diameter; and several, although occurring abundantly, could be found only within the space of a few rods. Only seventeen fresh-water species were found. Favourable stations for fresh-water species are rare.

In respect of the number of individuals of mollusca in Jamaica, as compared with more northern latitudes, the rule so obvious in the class of fishes is not applicable to the same extent. Of fishes, the species are much more numerous, but individuals much less so. Of the mollusca, the total number of individuals is about the same as in this latitude, and the number of species represented by a profusion of individuals is about the same. But the number of species not occurring abundantly is much greater, so that the average of individuals to all the species is less than in this latitude. From a comparison of the laws of distribution of the marine and terrestrial species in the Antilles, it follows that the number of the latter must exceed that of the former. With the insular distribution of the terrestrial species may be associated the fact, that the coral reefs are all fringing, for both facts are connected with the geological fact, that these islands are in a process of elevation.-Professor ADAMS before the American Association.-American Annual of Scientific Discovery, p. 334.

14. Metamorphoses of the Lepidoptera.-Professor Agassiz said that he had, during the past season, been studying the metamorphoses of the Lepidoptera, and, to his great surprise, he had found that one stage in the transformation of these insects has been overlooked by naturalists. We knew the Lepidoptera in three conditions, that of the worm, furnished with jaws and jointed, the chrysalis, and the perfect insect with four wings. The change not be

fore described, which he had noticed, is somewhat concealed under the skin of the caterpillar. The animal at a certain period swells at the thoraci region, and becomes extremely sensitive to the touch in this part, the skin being, in fact, in a state of inflammation. On cutting open the skin at this place, Professor Agassiz found beneath it a four-winged insect, before it had passed into the chrysalis state. The wings were long enough to extend half the length of the perfect insect. The posterior pair he found to be membraneous bags, somewhat flattened, like the respiratory vesicles of marine worms, with distinct ribs, which are blood-vessels. The anterior pair are also bags, with their upper half stiff and inflexible, like the elytra of coleoptera. The legs are tubular, but not joined, as in the perfect insect. The jaws are changed into two long tubes, which are bent backwards, as are also the antennæ. In the chrysalis, the wings are flattened and soldered together, as are the legs and sucking-tubes, which are bent backwards. The order of development of the different parts and the coleopterous condition at an incomplete stage, show that naturalists have been in error in placing chewing insects, as the coleoptera, above the sucking insects. The order should be reversed. Professor Agassiz said that he had confirmed his observations in many specimens, by examining them just at the moment when the skin begins to split on the back.-American Annual of Scientific Discovery, p. 327.

15. On the Zoological Character of Young Mammalia. -At the meeting of the American Association for the Promotion of Science, Professor Agassiz remarked, that zoologists have, in their investigations, constantly neglected one side of their subject, which, when properly considered, will throw a great amount of new light on their investigations. Studying animals, in general, it has been the habit to investigate them in their full grown condition, and scarcely ever to look back for their characters in earlier periods of life. We scarcely ever find, in a book of natural history, a hint as to the difference which exists in the young and old. Perhaps in birds, the colour of the young may be noticed; and it is generally known, that the young resemble the female more than the male; but as to precise investigation of the subject, we are deficient. But if the early stages of life have been neglected, there is one period in the history of animals which has been thoroughly investigated, for the last twenty-five years, -embryology. The changes which take place within the egg itself, and which give rise to the new individual, have been thoroughly examined; but, after the formation of the new being, the changes in its form which it passes through, up to its full grown condition, have been neglected. It had been his object to investigate this subject, because he had been struck with the deficiency there is on this point in our works; and in making this investigation, he had found that the young animals, in almost all classes, differ widely from what they are in their full-grown condition. For instance, a young bat, a young

bird, or a young snake, at a certain period of their growth within the egg, resemble each other so much, that he would defy the most able zoologist of our day to distinguish between a robin and a bat, or between a robin and a snake. There is something of high significance in this fact. There is something common to all these. There is a thought behind these material phenomena, which shews that they are all combined under one rule, and that they only come under different laws of development, to assume, finally, different shapes, according to the object for which they were introduced.

There is a period of life, in which, whatever may be the final form of their organs of locomotion, whatever may be the final difference between the anterior and posterior extremities, vertebrated animals have uniform legs, in the shape of little paddles or fins. This is the case with lizards as well as birds A robin's wing and a robin's leg, which are so different from a bat's wing and a bat's leg, do not essentially differ when young from the leg and arm of a bat. Wherever we observe combined fingers preserving this condition, we have a decided indication that such animals rank lower in the group to which they belong. This is all-important, as we are enabled at once to group animals which are otherwise allied, in a natural series, as soon as we know whether they have combined or divided fingers. And the degree of division to which the legs rise in their development is a safe guide in our classification. Look, for instance, at the legs of dogs and cats, in which the fingers are completely separated, and so elongated, that the animals walk naturally upon tip-toe, and compare them with others, bears, for instance, which walk upon the whole sole of the foot; and, again, with those of seals or bats, which remain united, and constitute either fins or a wing.

There are other reasons sufficient to convince us that the order of arrangement which he had assigned them, according the development of the fingers, is justified by the state of development of the other organs of the mammalia, and especially of their higher organs and intellectual faculties and instincts. And I will also add, says Professor Agassiz, that mankind are not excluded from this connection, but, in common with other vertebrata, we are all at one stage of existence provided with paddles or fins, which are afterwards developed into legs and arms.-American Annual of Scientific Discovery, p. 324.

16. The Manatus or Sea Cow, the Embryonic Type of the Pachydermata?-Professor Agassiz thinks that the Manati have been improperly considered cetaceans: they differ from them in the form of the skull, which is elongated, and in the position of the nostrils, which are in front. On the other hand, the skull resembles that of the elephant in front (particularly when seen from above), in some of the details of the facial bones, which are not like those of the cetacea, in the palatine bones, the arrangement of the teeth, and in the curve of the lower jaw. Professor Agassiz, believed