The species of this genus have not been investigated with much care. Four sorts have been found in our seas, which are probably the types of as many different genera. In two of these the sac is cylindrical above, and compressed towards the tail, with which the fins on each side are united.
In the Loligo vulgarly, the fins, together with the tail, form a rhomboidal expansion. The feet are nearly of the same length with the body, and covered with suckers only near their distal extremity. There is no eye-lid. The bone is elliptical, elongated, and produced at the upper extremity, with a groove along the middle. The appendage to the stomach is straight, and the oviduct is single.
This species is described and figured by Borlace, in his ?Natural History of Cornwall, p. 260. Tab. xxv. f. 27 ; and by Pennant in the British Zoology, vol. iv. p. 53. No. 43. Tab. xxvii.
• In the Loligo sagittata, the fins, with the tail, form a triangular expansion; the feet are shorter than the body, and covered with suckers nearly to their base. There is a duplicature of the skin round the eye, forming an eye-lid. The bone is narrow, thin, expanded at both ends, and strengthened by two marginal ribs, and one in the centre. The appendage to the stomach is spiral, and the oviduct double.
This species has hitherto, in this country, been con founded with the preceding. It is, however, the one alluded to by NIonro, secundus, in his Structure and Physiology of Fishes, p. 62. tab. xli. xlii. His specimens were prohahly obtained from the Frith of Forth. The same species has occurred to the writer of this article in the Frith of Tay.
In the two remaining species the fins which occur near the tail are not continued to its extremity. The Loligo media has the sac long, slender, and rounded. The fins on each side are of an elliptical form, and the tail is produced beneath into a point. This appears to be a rare species. It is figured by Pennant in his British Zoology, %al. 4, tab. xxix. No. 45.
In the Loligo sepiola, the body is nearly of equal di mensions in length and breadth ; the fins are thin and rounded, and the outline of tail semicircular. It is figured by Pennant in the British Zoology, vol. 4. tab. xxix. No. 46. This species appears to be rare. It is recorded by Pennant as having been taken off Flintshire, A specimen now before us was obtained in the Frith of Forth, at Kirkaldy, by Mr. Chalmers, surgeon of that town.
Various species of the Sepiacea were formerly used as food ; and Aristotle informs us that they were consi dered in the best condition for the table when nearly ready for spawning. The modern Italians and Greeks
are said to use them still as an article of diet, and to con sider the eggs as a great delicacy. In our own country, Mouffet considered them excellent meat, when boiled with wine and spices.
The animals of the second great division of the culla lopoda may be considered as nearly unknown. The shells were united by Linnxus in one genus, which he termed Nautilus ; but, in consequence of their peculiar characters, they have been sub•divided into many new genera. The animals belonging to two of these modern genera, spirula and nautilus, which both belong to the spiral multdocular tribe, have been imperfectly de scribed.
The shell of the Spirula has the whorls separate, the mouth orbicular, the chambers perforated by a tube, and the last cell produced into a tube. The animal resem bles the Sepia, and the shell is concealed under the skin, and occupies a similar situation to the cuttlebone.
The animal of the Spirula vulgaris appears to be very common in the Wrest Indies, as the chambered spiral extremity of the shell is frequently brought to this country.
In the shell of the restricted genus Nautilus, the turns of the spire are contiguous, the last whorl embraces the others on the sides, and the chambers are perforated by a tube. The animal of the Nautilus pompilius, accord ing to Rumphius, lodges in the last chambers, and is fixed by a ligament which descends into the tube. The arms which surround the mouth are destitute of suckers.
Among the minute shells which occur in the roots of sea-weeds, on old shells, corals, and sertularix, are many genera of multilocular testacea, some of which have been described in the article CONCHOLOGV. Guid ed by analogy, naturalists have been disposed to consider these as the productions of cephalopndous mollusca. Their inhabitants, however, have not been examined, and the task of doing so will be very difficult, as they are all very minute. When it is considered that a gastcropo dons mollusca bteathing air, Segmentina (Nautilus of Lightfoot) palustris, has its shell divided into chambers by transvei se partitions, and that the shells of some of the Annelides likewise exhibit appearances of being multilocular, the analogy loses its value, and we are dis posed to conclude that the true place in the systematical arrangement of animals, for the introduction of these minute shells, remains to be ascertained. Indeed, until the anie:als of the Spirula and Nautilus shall have un dergone a more minute investigation, the characters by which they are distinguished must be viewed with sus picion.