350 LOLIGIDJi J SEPIIDJE ; SPIRTJLID^. 



internal characters, especially the development of a chambered 

 shell, of which we find some traces in most of the different forms 

 included in it. Of the three great families into which this group 

 may be divided, the LOLIGID^E, commonly known as Calamaries 

 or Squids, are distinguished by their elongated bodies, with the 

 fins confined to the apex, and by the horny nature of the repre- 

 sentative of the shell, which consists of a slender stem, and two 

 lateral dilatations, giving it somewhat the aspect of a feather, 

 whence the name of pen is usually applied to it. The arms, and 

 especially the two tentacles, are generally of considerable length, 

 sometimes very long. In Chiroteuthis (Fig. 643), the tentacles 

 are sometimes six times as long as the body. The Calamaries 

 are all active, and swim rapidly. To this family belongs the 

 Loligo (Fig. 640), already several times referred to ; small spe- 

 cimens of this genus are frequently left on the beach by the tide 

 on our coasts, but the species are essentially inhabitants of the 

 open sea. In the Onychoteuthis the clubbed extremities of the 

 tentacles are armed with hooks, and the animals are said to em- 

 ploy the small suckers with which the bases of the clubs are 

 furnished, to unite them at this point, so as to form a pair of 

 grasping forceps with which they seize their prey. The SEPII- 

 DM, or true Cuttle-fish, are stouter in their form than the Cala- 

 maries, and their bodies are bordered throughout on each side 

 with a fin. The internal shell is a calcareous, laminated, cellu- 

 lar plate (the pounce-bone, which may be picked up on every 

 coast), usually presenting an indistinctly chambered apex. The 

 common Sepia, from which the Cuttle-Jish bone of the shops is 

 derived, is a native of British seas. The bone was formerly 

 used in medicine, but is now employed only for the formation of 

 pounces. The most evident approach to the tetrabranchiate forms 

 amongst the living Cephalopoda of the present order, is made by 

 the curious little family of the SPIRULID^E, of which a few spe- 

 cies exist in great abundance in the seas of warm climates, 

 where their singular shells may be picked up on almost every 

 sandy shore. These shells are spiral, with the whorls separate, 

 and the interior divided into several chambers by little trans- 

 verse partitions, which are penetrated by a slender siphon run- 



