330 S. I. Smith — Early Stages of Hippa talpokla. 



terminal segments more simple in form, the propodus being nearly 

 square, while the dactylns is small and acutely triangular, with the 

 tip obtuse. 



The posterior thoracic legs are exceedingly slender and, as in the 

 adult, are in life, usually at least, held concealed within the branchial 

 cavities. They are armed with comparatively few of the very slender 

 spinulose setae with which they are so abundantly furnished, espe- 

 cially toward the distal extremity, in the adult; and the series of 

 spinulose teeth upon the prehensile edges of the short fingers of the 

 cheliie are very short and composed of only a few individuals upon 

 each finger. There is no doubt that the peculiar position, structure, 

 and armament, of these slender posterior thoracic legs, in Hippa and 

 allied genera, specially adapt them for cleaning the branchiae and 

 branchial chambers of parasites and other foreign bodies. It is 

 worthy of note, in connection with this, that none of the maxillipeds 

 or thoracic legs possess any traces of either exipodal or epipodal 

 branches, some of the last of which perform the office of branchiae- 

 cleaners in the majority of the Brachyura and Macrura, 



The abdomen (Plate XLVITI, fig. 4), when fully extended, is about 

 as long as the carapax and resembles that of the adult in the form 

 and proportions of the segments, but differs essentially in the struc- 

 ture of the appendages, especially those of the second to the fifth 

 segment, as is usual in the megalops-stage. The. first segment,* as 

 seen from above («, fig. 4), is a small plate, with the outline of the 



* Latreille and Milne-Bdwards have mistaken this small first segment of the abdo- 

 men of Remipes and HiiJjM for the last segment of tlie thorax, and I am not aware 

 that the mistake has been corrected by any subsequent author. Latreille (Genera 

 Orustaceorum et Insectorum, i, p. 45) simply says of Reviipes iesiudinarius, " Cauda 

 segmento baseos aliis multo latiore." But Milne-Edwards (llistoire naturelle des 

 Crustaces, ii, pp. 203, 206, 208), after saying in the description of tlie genus Albunea, 

 "Le premier anneau de I'abdomen est petit, et regu dans une echancrure de la carapace ; 

 le second est au contraire tres-grand et presente de chaque cote un grand prolongement 

 lamelleux," goes on to say, under the genus Remipes, " Le dernier anneau thoracique, 

 qui porte ces appendices [les pettes posterieures], est complet en dessus, mobile, et pas 

 reconvert par la carapace, de maniere qu'on pourrait facilement le prendre pour le 

 premier segment de I'abdomen. Celui-ci est tres-grand, et presente de chaque cote 

 un prolongement lamelleux ovalaire qui chevancho sur la carapace; son bord posterieur 

 est echancre pour loger le second anneau abdominal, qui est ovalaire j * * * * je 

 cinquieme et la sixieme sont egalement petits, mais sent sondes entre eux. * * * * 

 Les trois premiers anneaux portent, chez lafemelle, des filits oviferes simples." Under 

 Hippa, he further says, " Le dernier anneau thoracique u'est pas libre et a decouvert 

 comme chez les Remipedes ; mais le premier article de I'abdomen est a pen pres de 



