48 PROCEEDINGS OF THE NATIONAL MFSEVM. vol. x.xxi. 



Bay of Biscay, 800-1,900 meters (A. Milne-Edwards and Caullery); 

 west coast of Ireland, 3S2-(jO0 fathoms (Holt and Tattersall); Azores, 

 1.000 meters (Hansen); near Maldive Islands, 430 fathoms (Alcock and 

 Anderson). Typical form ^ as G. loillenioesi : Banda Sea, 1,425 fathoms 

 (Sars); Gulf of Panama, 1,270 fathoms (Faxon); off Aeapulco, 193-664 

 fathoms (Faxon); Tres Marias Islands, 680 fathoms (Faxon); Hawaiian 

 Islands, Molokai and Hawaii, 552-809 fathoms (Ortmann). 



G. zoeamrsl: Bay of Beng-al, 840 fathoms (Wood-Mason); Hawaiian 

 Islands, vicinit}^ of Kauai and Modu Mann, 293-800 fathoms (Ortmann). 



THE LARVAL FORM OF GNATHOPHAUSIA ZOEA. 



As previously mentioned, among the material is a large female of 

 this species, representing Sars's form G. willemots!^ which has the mar- 

 supial pouch fully developed and filled with larva\ Since larval stages 

 of this genus have never been described, indeed, since nothing is 

 known about the development, with the exception that on account of 

 the presence of a marsupial pouch and in analog}^ to LophoiiaHter it is 

 presumed that the development of the 3'oung form probal)ly reaches a 

 ver}^ advanced stage before it leaves the motliei-, it is advisable to give 

 here a more detailed account of these young specimens. 



The number of the young is 21, a remarkabh" small number, but 

 agreeing well with what we know about the numlier of the progeny of 

 deep-sea animals. They are all uniformly developed and represent a 

 verv advanced stage, in fact, they are no longer eml)ryos, but have 

 left the egg completely. Probably they were a)>out ready to leave the 

 pouch of the mother, as all parts of the body had attained, in a general 

 way, the condition found in the free swimming form. 



Within the pouch the young Gnathophausite are so arranged that 

 they lie firmly packed together, the head of each directed toward the 

 posterior end and the sternum of the mother, and the tail toward the 

 anterior end of the mother, each overlapping in part the individual in 

 front of it. That is to sa}^ the heads are directed toward the liases, 

 the tails toward the tips of the marsupial lamella. The dorsal face of 

 the larvffi is concave, the ventral face convex, corresponding to the 

 curvature of the lamellae, since the back is turned toward the sternum 

 of the mother, the ventral side toward the enveloping lamella\ 



In each of the young ones (see Plate II, fig. %i) the body is distinctl}^ 

 divided into an anterior (thoracic) and posterior part, which forms a 

 distinctly and completeU' segmented abdomen. The carapace is rep- 

 resented b}^ a bag-like excrescence, which is provided with distinct 

 and long rostral and postero- dorsal spines. It is filled wnth the rem- 

 nant of the yolk. Its keels are very indistinct, but there is a small 

 point posteriorly on each side, possiblj^ representing the postero-infe- 

 rior corners of the carapace. The dorsal spine is long and closely 



