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HANDBOOK OF INVERTEBRATE ZOOLOGY. 



Considerable change has now taken place in the shape 

 of that portion of the yolk which is contained in the head. 

 It is reduced to a long, narrow tube (y"), which connects 

 the portions contained in the body proper (//", y""), with 

 the external yolk sac (.y')- The pulsatile space (x), be- 

 tween the outer wall and the surface of the yolk sac, is 

 more plainly shown in this figure than in the preceding 

 ones, although a profile view shows it with equal distinct- 

 ness at earlier stages. 



Fig. 202 is a posterior view 

 of an embryo a little older than 

 the one shown in Fig. 201. A 

 large rounded prominence on 

 each side of the head marks the 

 position of the eye-stalk, and the 

 eyes are farther forward than 

 they are in older specimens, but 

 in other respects the form is very 

 similar to that of the adult. The 

 ink sac (i) has appeared, and is 

 filled with ink, and the tip of the 

 free portion of the rectum is pro- 

 longed at its corners into the pair 

 of ear-like anal valves. 



FIG. 202. A free swimming squid, 

 with the external yolk entirely ab- 

 sorbed. (Drawn from nature by W. K. 

 Brooks. ) 



The letters as in the preceding fig- 

 ures. 



There are considerable individual variations in the ar- 

 rangement of the chromatophores, but there are certain 



