and saline manures, such as guano, salt, plaster, lime, &c., experiment with them repeatedly and accurately on the small scale, so as to learn what the crops say about their value. Where phosphates have been heavily applied, it is probable that ammonia or nitrogenous manures, or perhaps lime or potash, may next exert the most beneficial action, and vice versa. Be sure of enough, not only as regards the quantities, but also the kinds of matters applied.

But our subject requires treatment which only a volume can give space for. The recent progress of knowledge, thanks to the scientific farmers and agricultural philosophers of England, Germany, and France, demands a series of chapters on manures that are as yet unwritten, but, when rightly produced, will be alike novel, interesting, and useful to the true American farmer, who cultivates with equal assiduity the "soil and the mind."

LECTURES

ON THE SHELLS OF THE GULF OF CALIFORNIA.

BY PHILIP P. CARPENTER, OF WARRINGTON, ENGLAND.

The pearl fishery carried on by the Spaniards in the "Sea of Cortez" during the 17th and 18th centuries, bore testimony to its richness in molluscan life. To obtain the "pearl oysters, eight hundred divers were regularly employed, and the annual value of the exports was $60,000. So exhaustive was this fishery that it was gradually abandoned; and the very limited trade between the gulf ports and the Old World did not lead to more than the most fragmentary knowledge of its marine fauna. A few of the shells of Acapulco had been brought home by Humboldt and Bonpland as early as 1803; and collections had been made at various stations on the Central American coast by Captain Beechy and Lieutenant Belcher, R. N., in the voyage of the Blossom, 1825-1828; by MM. Du Petit Thouars, La Perouse, and Chiron, in the Venus, 1836-1839; and in the Sulphur, by Sir E. Belcher and Mr. Hinds, in 1836-1842. The shells of Panama and the coast of Ecuador, closely related to those of the Gulf of California, had been obtained in great abundance by Hugh Cuming, esq., whose vast collection of shells is not only by far the largest in the world, but, through the generous courtesy of its owner, the most accessible to students of every nation. Scarcely any shells, however, had been collected in the gulf, and indeed the records of scientific voyages, rich as they are in additions to our knowledge of fresh forms, rarely afford satisfactory data as to the fauna of any particular district. Unfortunately, it has been the custom, in the accounts of these voyages, only to describe the (supposed) new species; besides which, the locality marks, even if accurately noted at the time, are exposed to many chances of error before the information is made accessible to the scientific world.* Whether the shells of the gulf most resembled those of Panama or those of California, (which were described by Mr. Conrad from collections made by the late Mr. Nuttall in 1834,) was still a matter of doubt up to the period of the Mexican war in 1846-'8. When Major Rich and Captain Green visited Mazatlan, they became acquainted with a Belgian gentleman, M. Reigen, who had been employing himself in making a vast collection of the shells of that region. This collection ultimately passed into the hands of a merchant who

The works of Mr. Hinds are, however, in every respect reliable, in consequence of the great skill and accuracy of the lamented author.

divided it into two portions: the smaller was sent to Havre; the larger, occupying no less than 560 cubic feet, to Liverpool.

A collection of such magnitude, known to have been made only at one spot, had never before been thrown open to the public; and, knowing that its contents were likely to afford very valuable information in reference to the geographical distribution of species, I embraced the opportunity which circumstances afforded me to pass the whole under careful review. The result of my labors will be found in a "report on the present state of our knowledge of the mollusca of the west coast of North America," prepared at the request of the British Association for the Advancement of Science, and published in the volume of transactions for 1856; and, in a more detailed form, in the "descriptive catalogue of the Reigen collection of Mazatlan mollusca" printed by order of the trustees of the British Museum, 1857.* The best duplicate series, amounting to about 6,500 shells, I have lately given to the State of New York. Having come to this country to arrange it in the natural history rooms at Albany, Professor Henry requested me to visit Washington, and arrange the shells of the United States exploring expedition. For this difficult task, the sorting out of the Mazatlan shells, amounting probably to 100,000 specimens, was perhaps no unfit preparation.

In the present lecture, it is proposed to confine our attention to a single shell from this collection. It belongs to a group nearly related to the oysters, and still retains the name of Spondylus given to it by Aristotle more than two thousand years ago, from the resemblance of the thorny processes outside the valves to the vertebræ of the higher animals. I have named the species calcifer, from the use made of it by the natives, who dive for it in order to burn for lime. Its solid, ponderous growth affords a striking contrast to the great "water-clam" of the Pacific islands, in which the shell-layers are generally separate from each other.† Unfortunately the cumbrous size of these shells led the Liverpool dealer to dispose of the whole stock before I had an opportunity of examining them; their ignominious fate being to adorn the "museum" of a large drinking saloon, the owner of which had no idea of their scientific interest, and was unwilling to part with any of his duplicates. The very few which fell into my possession proved, however, to be a little museum in themselves; each specimen so abounding in parasites, within and without, that I have described upwards of a hundred entirely new forms of molluscan life derived from this source alone; besides about 250 others which had been previously investigated, or which are not yet determined; and a variety of Annelids, Crustaceans, Zoophytes, Sponges, Protozoas, Protophytes,

Both of these works are in the library of the Smithsonian Institution. In order to aid in their compilation, Mr. Herbert Thomas purchased for me what remained of the Reigen collection. The first fruits of this, amounting to nearly 9,000 specimens, I presented to the British Museum.

† A very remarkable specimen of this shell was brought home by the United States exploring expedition, in which the free as well as the attached valve displays the long, flat, triangular ligament area, presenting somewhat the appearance of the gigantic fossil Plagiostomata.

and algæ, which are yet awaiting the attention of naturalists acquainted with those special departments. We propose first to examine the creatures which make their abode on the outside of these oyster valves.

Certain smooth, oval spaces bear testimony to the former presence of many kinds of limpets. Some of those creatures, (as e. g. the Patella Mexicana, or giant limpet, which is sometimes a foot in length and large enough for a basin) prefer to live on the rocks; others are always found on dead shells; others again always adhere to living ones. The circulation of water caused by the breathing currents of the larger animal is no doubt congenial to their tastes. Most mollusks have the power not only of forming, but also of absorbing shelly matter; and these limpets, by the constant action of their strong muscular foot, eat into the shell of the spondylus and leave a mark by which each species can generally be recognized. Some of them make regular excursions to browse on the algae and nullipore which they rasp off with their thousand-toothed lingual ribbon, always returning to their own hole to sleep; but others appear to lead a sedentary life, depending, like the bivalves, on whatever nutriment the water brings within their reach. These, which go by the common names of "bonnet," "slipper," or "cup-and-saucer" limpets, are more highly organized than their more active neighbors; the gill being a delicate little comb at the back of the neck, and the sexes being distinct. The Calyptræids ("slipper" and "cup-and-saucer" limpets) found on the Spondylus valves are the most beautiful and varied that are known in any part of the world. The shells are large and thin, delicately furrowed, and as it were engine-turned with a profusion of tubercles, which sometimes rise up into long hollow spines. The colors vary from white to a rich black-brown, or are variously mottled with sienna, while the shape may be either an elevated cone or a widely spreading disk. Sometimes the same individual will begin with one form and sculpture-pattern, and suddenly change to another; others again seem to develop permanent and widely differing varieties. Occasionally a starved or diseased Mazatlanian will present the aspect which is normal on the colder shores of South America; exchanging its thin texture and delicate sculpture for a coarse, solid, and nearly smooth shell. So far the views lately propounded with such ability by the celebrated author of the Voyage of the Beagle" meet with sufficient confirmation; and yet, amid all its changes, there is a habit of growth, hard to describe and yet easily recognized by the practised eye, which not only unites the most aberrant forms, but at once separates them from neighboring species found on the same coast and appearing very similar to the common observer. The ordinary plan of only preserv ing in collections a few picked specimens displaying marked peculiarities, is by no means favorable to the elimination of truth in reference to specific variation. These extreme forms are very naturally described as distinct species, the intermediate connecting links not passing before the view of the naturalist. On showing to a distinguished author a carefully eliminated suite of Mazatlan specimens connecting the smooth, thin, flat Crepidula squama, Brod. with the

66

coarse, arched, laminated C. Lessonii, passing through the forms C. nivea, C. B. Ad. and C. striolata, Mke., he complained that I had "kept all the puzzling shells." In the very useful work of Messrs. H. and A. Adams on the genera of recent Mollusca, these forms appear under different subgenera.* It is not fair to blame authors for these mistakes, which naturally result from the imperfection of the material on which they work. But the prevalence of such errors should lead us to embrace every opportunity of studying large numbers of specimens, both from the same and from different localities. Patience, accuracy, and honesty may thus render as valuable service to science as brilliant genius, and may supply the materials from which some master-mind may hereafter develop the most important generalizations.

Those who describe species from minute differences founded on individual specimens, might do well to study the plates appended to the "B. A. report on the West Coast Mollusca" before quoted. Take, e. g., the Crucibulum spinosum, pl. 9. The shell is at first spiral, like a snail. It then surrounds its entire margin with a rim, which is the first beginning of what in the adult becomes the "saucer," or outside shell; that is, the hardened skin of the animal's body; (for shells are not to be regarded as a house constructed for the animal to live in, but as an integral part of the animal itself, like the feathers of birds or our own nails and hair.) At the same time it raises a slight lamina from the labium, or "pillar-lip," which ultimately becomes the "cup." At first, however, it is like the "deck" in the slipper limpets, from some species of which it can scarcely be then distinguished. The Crepidulæ, however, continue their deck in a horizontal direction, while the Cru

Fig. 1.

cibulum turns the edges upwards at a more or less obtuse angle. Gradually, during the progress of adolescence, this angle becomes right and then acute; the outer shell meanwhile taking various forms, round, oblong, or irregular, according to the nature of the surface to which it has chosen to adhere. Often this immature state is continued to a late period; if permanent, it would belong to the subgenus Dispotæa (Say) of Messrs. Adams. But, normally, the sides of the cup close in, while its body becomes greatly swollen in front. This cup now assumes the form which is always characteristic of the species under every modification of external growth; being well rounded in C. imbricatum, angular at the side in C. spinosum, and with the sides flattened against each other in C. radiatum. In C. rude, the adolescent stage is very soon completed, and the cup is permanently detached from the side of the shell, forming a veritable cup and saucer," one, too, after the fashion so prevalent in America, where the cup-handle has never been formed.

Crucibulum imbricatum, jun. Interior view, showing the cup lamina beginning to double in.

*The plan adopted by D'Orbigny in his classification of Foraminifera, was to pick out from a large mass of material the leading forms; which he grouped into genera, families, and orders. In my brother's papers on Orbitolites, &c, in the transactions of the Royal Society, it is shown that individuals belonging, according to D'Orbigny, to different orders are really aberrant forms of the same species.