252 



THE SEA SHORE 



have but eight arms, the other two appendages being really ten- 

 tacles, which are usually longer than the arms, and more or less 

 retractile ; they are also expanded at the ends. The decapods 

 are also to be distinguished from the octopods by their elongated 

 bodies, and a flattened, fin-like appendage on either side. Their 

 eyes, also, are capable of being rotated within the orbits, while 

 those of the octopods are fixed ; and the shell consists of one or 

 more horny 'pens,' or of a calcareous 'bone,' contained in a cavity 

 so loosely that it drops out of its place when the cavity is opened. 



The Common Calamary (Loligo vulgaris) may be recognised 

 by the accompanying illustration, from which it will be observed 



FIG. 184. Loligo vulgaris AND 

 ITS PEN 



FIG. 185. Sepiola atlantica 



that the body tapers behind, bearing two rhomboidal fins in the rear. 

 The suckers are arranged in two rows on the arms, but in fours on 

 the expanded tips of the tentacles. The animal is a good swimmer, 

 and sometimes crawls, head downwards, on the disc surrounding 

 the mouth, pulling itself along by means of its arms. Its shell is 

 a horny pen, lanceolate in form, but it divides as the age of the 

 animal advances, so that two or more may be found in the same 

 specimen. 



Belonging to the same family we have the Common Squid 

 (Sepiola atlantica), also a very abundant species. Here the body 

 is shorter and purse-like, and the fins are dorsal and rounded. It 



