474 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 88 



a terminal chitinous process with a small spinule. The chitinous 

 framework supporting the peg continues to the posterior proximal 

 edge of the basis across the dorsal side of the segment, where the 

 chitin is thickened conspicuously. On the female the posterior por- 

 tion of the coxa of this appendage protrudes and will be the natatory- 

 lobe of the adult. 



The abdomen differs in shape with the sexes. On the male the 

 lobes are larger and bluntly pointed while the smaller ones of the 

 female are rounded. 



After the seventh stage there is no well-defined characteristic; the 

 change brought about by molting is merely in grade. The earlier 

 stages are very regular, but the later stages, after the fourth, are 

 very irregular and hard to define. 



Molting takes place by rupture of the exoskeleton along the mid- 

 line from the anterior marginal groove to the anterior thoracic seg- 

 ments. The animal draws out the thorax and abdomen through this 

 slit first. Then the anterior portion of the carapace is withdrawn 

 and finally the lateral lobes. This ecdysis occurs over the whole 

 body except the coat of the suction cups, which comes off after the 

 molting process of the other portions is through. 



Subsequent developTnent. — From this time on the lateral lobes of 

 the carapace enlarge, and all the grooves on the dorsal surface be- 

 come distinct while the longitudinal groove appears later. The 

 ramifications of the stomach become more complicated, and pigment 

 spots on the oviduct appear about the twentieth day after hatching. 

 The suction cup loses the residual portion of the maxilla except a 

 tiny seta, which remains for a long time. A papillated process on 

 the anterior margin of the precoxa of the third leg and small proc- 

 esses in front of the aperture of the socket of the male are formed 

 at a later stage. 



The abdomen grows somewhat and the animals become sexually 

 mature during these molts. Development is completed about one 

 month after hatching. 



It will be noted that the account by Tokioka describes seven well- 

 defined larval stages with subsequent molts, which serve to bring 

 the animal to sexual maturity. Wilson was indefinite as to the num- 

 ber of molts, but in one place indicated that he had observed four. 

 It is also worthy of note that no mention is made of any maxillae 

 within the proboscis and that the two pairs of appendages imme- 

 diately behind the proboscis are called first and second maxillae. 



