didymis, and even higher up the gland, for in general all these parent or secondary cells are thrown into the spermatheca of the female before they burst. Preparations, however, for this destruction of the parent cell seem to be going on in the vas deferens of the male a long time even before the testicle has arrived at its maximum state of periodic developement, for the difference between the cells in the epididymis and vas deferens is quite apparent. Those in the former are quite full of young cells, the walls of the parent cell lying tightly and closely upon, and binding them together as it were; whereas those in the latter, although quite distended, are not full altogether of cells, but with a fluid which appears to separate the young contained cells from one another, and from the walls of the parent cell. If a female crab can be procured shortly before spawning, the spermatheca will be found quite full of these young cells, which we shall henceforth term primary, or spermatozoal cells, with a few parent or secondary cells floating amongst them. If the crab is still farther advanced, we will find that these secondary cells have disappeared altogether. These cells in the spermatheca are suspended in a thick albuminous fluid of a milky colour. Throughout the whole course of the testicle and epididymis, we find floating in a thick glairy fluid, along with the cells, in masses of an irregular-shaped, clear-looking appearance, a substance which apparently forms the nutriment of the cells, for this substance is always found in greatest quantities high up the organ, where the secondary cells are in an active state of growth and secretion, and of course requiring a supply of nourishment; whereas in the vas deferens, after the cells have arrived to a state of maturity, little or none of this substance is found. How this substance is secreted, or in what part of the organ, I have not yet been able to ascertain. The above description of the secretion and developement of the seminal fluid refers to all the Crustacea. It will be found, however, that this fluid varies more or less in its character in almost each species. In the May and June Nos. of the Ann. des Sc. Nat., a translation of a paper will be found, "On the Seminal Fluid of the Crustacea and Cirripeda; by M. Kolliker of Zurich. That gentleman, in the above paper, looks upon the filiform bodies which are found in such numbers generally in the interior of the testicle of the lower crustacea, as the spermatozoa. Now, as far as my observations have gone, it appears to me that these are parasitic entozoa (Filaria). My observations had been directed to these animals sometime before I had seen M. Kolliker's paper, at which time I had made up my mind as to their parasitic character, and for the following reasons: From observations on the origin and developement of the spermatozoa in the higher Crustacea, it had been made out that these were developed from cells, and from cells only. Now in every instance these Filaria were always found to be the same, never changing their characters in the slightest degree. Besides, the developement of the seminal cells in these lower Crustacea, was always going on in the same way as it did in the higher, and with

out any appearance in the primary cells of the enclosed bodies, being like these Filaria. This, of course, also extends to M. Kolliker's observations on the same fluid in Cirripeds, for they must be looked upon now as Crustaceans also.*

As the ova pass through the spermatheca, they come in contact with the spermatozoa, and in this way are impregnated. They also appear to obtain in this organ a thick coating of albumen, which afterwards becomes the ovisac.

The organs employed in this class of animals for the proper defence of the ova, after they have been excluded from the ovaries, and during the time they are attached externally to the mother, are very interesting. After a careful analysis, they will be found throughout the whole class to be either legs not fully developed, or parts of these organs very much developed. The first of these divisions will be found to exist in the higher Crustacea, such as those belonging to the Brachyura, the Anomoura, and Macroura; this form is also found in the Araneiformes. It is in the Stomapoda we first observe these organs assuming another character, namely, that of protecting scales. We find this character gradually making its appearance, however, in the lower Macroura, as in Hippolyte and Palemon, where we find the ova attached by means of filaments to broad scales, and in the other genera; if this is not present, the usual armature of the body will be observed enormously developed, so as in some cases almost to meet, by means of their edges, on the abdominal surface of the body.

In the Amphipoda, Læmodipoda, and Isopoda, we find these ovigerous scales bearing a considerable resemblance to those of the Stomapoda. In the Branchiopoda this character still exists, but in rather a more interesting form. In Apus we find the ova contained in a cavity formed by the expansion of the first joint of the eleventh pair of legs into two large circular-shaped and hollow plates, which, when closed together, form a safe means of defence. Through the genera Branchipus, Artemia, & c., we are led to Daphnia, Polyphemus, and Evadne, where we find this means of defence in its maximum state of developement, namely, one, or perhaps more, pairs of legs enormously developed, so as not to cover the ova only, but the whole body. The occurrence of this in these animals, is the cause of their unusual and grotesque appearance. From this form we are more suddenly brought through Saphirina and Cetochilus to the Monoculi, where we find a different means of defence altogether. Instead of great developement of the feet, we find one pair, or perhaps more, of these organs aborted altogether, and sacs or bladders are secreted each time the animal becomes loaded with spawn. This form is carried into, and continued throughout all the Siphonostoma, until we reach the Araneiformes, where we again find these organs assume almost the same appearance as those with which we first

* Edinburgh New Philosophical Journal for July 1843.

Vol. 35,

p. 88.

commenced, but perhaps more like ordinary feet, to which the ova are
attached in small round pellets.

The metamorphosis of the larvae are peculiar and interesting. They
afford good characters for the definition of the higher divisions of the
class, and even good and strong specific characters.

W. 5; NW. 1; N. 14; NE. 0; E. 19; SE. 0; S. 0; SW. 1; Var. 2.

W. 17; N.W. 3; N. 4; NE. 1; E. 3; SE. 0; S. 0; SW. 1; Var. 1.

At Kinfauns, the extremes of pressure during June were 30.24 and 28.40; extremes of temperature 78° and 41°; mean temperature 57°.10; mean temperature of June last year at Kinfauns 55°.86, last month being warmer by 1°.24; whereas here there is a difference of nearly six degrees (viz. 5°.71) betwixt the June of the present year with the corresponding month of 1842; amount of rain 2.10 inches.

TIDAL PHENOMENA.

Arbroath.-A singular phenomenon has lately been very frequently observed at our harbour. When the tide is making, the tide will come rushing two or three feet into the harbour, at the rate of four miles an hour, for ten minutes or so, and all at once turn and rush out again as fast, and again turn and pour into the harbour with its former violence, and continue frequently to advance and recede, when, apparently without any cause, it will resume its former quiet manner of fulfilling its destinies. At Perth, Leith, and at Valetta in Malta, the same phenomenon has occurred, and has been ascribed to earthquakes.

Campbeltown.-On the afternoon of Friday the 7th day of July, an extraordinary motion of the tide was observed here (Fort George). While some carters were employed in lading with timber a vessel on the beach about low water, the tide suddenly advanced 50 or 60 yards, surrounding men and horses with a depth of water of about 18 inches, and as rapidly retired. This rise and subsidence occurred four or five times in succession, within a short period.

The same phenomenon appears to have been observed at Valetta, in Malta, the water suddenly rising to the height of three feet, and overflowing the works of the new dry-dock. During this period, a very strong current was running out of the harbour, which the boatmen could scarcely stem. It is supposed this circumstance must have occurred through some earthquake at a remote distance.

Leith.-A very singular phenomenon was observed here on Friday the 7th July. At low-water the tide suddenly rose about six inches, rushing into the harbour, and in a few minutes again receding with equal velocity.-Vide Berwick and Kelso Warder for July 22 and 29, for further particulars.