3302 THE MOLLUSKS OR SHELLFISH 



pods are provided with an internal shell. That of the living species is either horny 

 the so-called pen (gladius~); or else calcareous the bone (sepion} of the cuttle- 

 fish. In Spirula the shell takes the form of a tube, beautifully coiled, and divided 

 off into numerous air chambers by a series of septa or partitions. The arms of the 

 decapods are furnished with pedunculated suckers, armed with horny rings or hooks. 

 The head is invariably distinct from the body. The eyes are. free and movable, and 

 either covered with a fixed, transparent lid or skin, or unprotected and in immedi- 

 ate contact with the water. All the species have either lateral or posterior fins, and 

 the funnel is provided with an internal valve. They live for the most part out at 

 sea, but some Sepia, for example are met with nearer the shore. The pelagic 

 forms are often found in immense shoals, and are eaten in enormous quantities by 

 many cetaceans and large fishes. When pursued by their enemies, squids have 

 been known to dart out of the sea with such force as to fall upon the deck of a pass- 

 ing vessel. Decapods may be classified in three sections, according to the charac- 

 teristic of the shell, of which the different types have already been mentioned. 



SQUIDS Family 



Some of the commonest of the horny pen-bearing decapods are the true squids 

 or calamaries (Loligo}, which have a more or less elongate body, with very large lat- 

 eral fins at the posterior end. The eight sessile arms are provided with two rows 

 of suckers with toothed horny rings, and the two tentacular arms are long, slender, 

 and terminate in an expanded club, bearing four rows of suckers. The pen is large, 

 horny, as long as the body of the animal, and placed beneath the skin of the back. 

 It is not in any way attached, so that if the skin be slit open, the shell can be drawn 

 out entire. The common squid (Loligo vulgaris) is met with all round the British 

 coasts, and occurs in shoals of greater or less extent in the Mediterranean and 

 Atlantic. The spawn consists of numerous, long, semitransparent, gelatinous 

 sheaths, radiating from a common centre. Each sheath is about four inches in 

 length, and contains numerous ova, and it has been computed that in a single mass 

 of sheaths the deposit of one female contained as many as forty-two thousand per- 

 fect young squids. Mr. L,ee observes that he has never seen these ' ' sea mops ' ' 

 attached to anything; and the pelagic habits of the calamaries render it probable 

 that they are left floating on the surface of the sea. They are deposited in May or 

 June. The calamaries are active animals, and always in motion. A second genus 

 of squids (Ommato strep he 's) , frequently regarded as representing a distinct family, 

 differs from Loligo in having the body very long, the posterior fins comparatively 

 short, and the pen very narrow. They are gregarious, and frequent the open seas 

 in all latitudes, and are extensively used as bait in the cod fishery off Newfound- 

 land, and also constitute the principal food of dolphins and the sperm whale. They 

 are also largely eaten by the albatross and other marine birds. By sailors they are 

 called "sea arrows" and "flying squids," on account of the rapidity of their 

 movements and their habit of leaping out of the water. It is said that they fre- 

 quent the shore in pursuit of the fry of pilchards and other fishes. 



