246 



CEPHALOPODA. 



noted, viz. the oral (fig. 1 1 1 B, m) and anal invaginations, the 

 latter of which is extremely shallow and appears at the apex of 

 a small papilla which may be spoken of as the anal papilla. 

 These invaginations appear at the two opposite poles (anterior 

 and posterior) of the blastoderm. Shortly after this the rudi- 

 ment of the first pair of arms arises considerably in front of the 

 other rudiments, at the sides of the outer pair of cephalic swell- 

 ings (fig. 1 1 1 B, i). 



Fig. 1 1 1 B represents a view from the dorsal surface of an 

 embryo at this stage. In the centre is the mantle with the shell- 

 gland which is now very considerably raised beyond the general 

 surface. Concentric with the edge of the mantle are the two 



cc 



FIG. in. SIDE VIEWS OF THREE LATE STAGES IN THE DEVELOPMENT OF 



SEPIA. (After Kolliker.) 

 m. mouth ; yk. yolk-sack ; oc. eye ; mt. mantle. 



halves of the funnel, the anterior half meeting the dorsal or neck- 

 cartilage and the posterior halves approaching each other. The 

 oral invagination is shewn at m and the anal immediately in 

 front of an. The gills, nearly covered by the mantle, are seen at 

 br. At p are the cephalic swellings, and the eye is seen at oc. 



