286 THE . SCHIZOPOD A. 



shorter with the exopod setiferous but no endopod. Third to fifth pair nearly 

 rudimentary, oblong, with a transverse suture but without setae. — The uropods 

 reach nearly the proximal pair of spines on the terminal part of the telson. 

 This terminal part (fig. Ig) is very different from that of first Furcilia-stage ; 

 the terminal margin is convex with on!}- fi\'e spines and the median spine longer 

 and stronger than tlie others, wliich are a little shorter than in the earlier stage; 

 of the distal lateral spines the intermediate pair are nearly as in the preceding 

 stage (in the single specimen the left spine is normal, the right shorter and without 

 fine marginal spines), the proximal pair are short and slender, while the distal 

 pair are longer and stronger than the intermediate, straight, with only two or 

 three fine spines on the inner margin. 



Length of the single specimen 5 mm. 



The specimen is from "Albatross" Sta. 4710; December 30, 1904. Surface. 



Remarks. — That the two stages described belong to the same species is 

 easily seen from the shape of the frontal plate, the antennulae, the eyes, and the 

 second abdominal segment. It is closely allied to T. monacantha Ortm. (T". 

 agassizii Ortm.) but can scarcely be that species. The "Siboga" material 

 contained specimens of the last Furcilia-stage, furthermore a young animal in 

 which the process from the two proximal antennular joints had begun to develop 

 — so that this specimen could with absolute certainty be referred to T. niona- 

 cantha — and besides two stages intermediate between the last-named speci- 

 men and the last Furcilia-stage, and it is quite sure that all these specimens 

 belong to the same species. But the specimens in the last Furcilia-stage from 

 the "Siboga" differ from the specimen in the Agassiz collection just described 

 by ha\-ing the body a little shorter and somewhat more clumsy, the ej^es some- 

 what larger, the frontal plate a little different in shape, the second abdominal 

 segment less protruding above and besides showing an interesting difference in 

 the telson. Though the thoracic and abdominal appendages show the same 

 degree of development in the specimens in last Furcilia-stage from both col- 

 lections, the Agassiz specimen, which is a little longer than those from the 

 "Siboga," has the distal part of the telson less developed than the "Siboga" 

 specimens, as the long postero-lateral spines of the intermediate pair found in 

 the Agassiz specimen are lost in the "Siboga" specimens (Siboga-Exp., 37, 

 pi. 13, fig. 3g). 



It is, I think, \-ery improbable that the differences pointed out between 

 specimens in the last Furcilia-stage from the Indian ^\i-chipelago and the tropical 

 East Pacific can be found in larvae of the same species from two distant areas. 



