Indian Deep-sea Crustacea. 279 



Parapen^eus, S. I. Smith. 

 Parapenams investigatoris^ sp. n. 



Allied to Parapenams jissurus, Sp. Bate, having - the same 

 branchial formula as we described for that species in Journ. 

 Asiat. Soc. Bengal, vol. lxiii. pt. ii. 1894, p. 144 (from which, 

 by a copyist's error, the epipodite on appendage 8 was 

 omitted); the same longitudinal and vertical fissures in the 

 carapace ; a similar dorsal carina, bearing a single sharp tooth 

 on the gastric region, and produced into a rostrum ciliated 

 inferiorly, furnished with six teeth superiorly; a similar 

 compressed abdomen, with the carina of the fourth, fifth, and 

 sixth segments ending in a small tooth covering a small 

 V-shaped notch in the posterior dorsal margin of the fourth 

 and fifth segments ; and a very similar telson and svvimmeret. 

 It can at once be distinguished from Parapenams jlssurus, 

 of which there are two ' Challenger ' specimens from Zebu in 

 the Indian Museum, by the presence of a well-marked sharp 

 branchiostegal tooth placed slightly behind the anterior 

 margin of the carapace, and not on it as in Spence Bate's 

 species. It further differs in the length of the rostrum, 

 which reaches only just beyond the end of the first joint of 

 the antennulary peduncle instead of beyond the end of the 

 second joint ; in the rostrum sloping gently upwards in its 

 proximal, gently downwards in its distal half; in the relative 

 shortness of the carapace, which, exclusive of the rostrum, is 

 only very little more than ^ the length of the abdomen 

 instead of nearly \ the length ; in the great relative length of 

 the sixth abdominal segment, which is 2^ times the length of 

 the fifth segment instead of about If times its length ; in the 

 third abdominal segment being non-carinate ; in the inner 

 plate of the swimmeret extending for about \ its length 

 beyond the extremity of the telson ; in the inner branch of 

 the antennulary flagellum being slightly the longer, nearly as 

 long as the carapace exclusive of the rostrum, and gradually 

 expanding at its base, while the outer branch expands 

 suddenly into a base considerably thicker than that of the 

 inner branch ; in the " thelycum " being of a different struc- 

 ture ; and in never appearing to grow to the same size as 

 Penams Jissurus. 



5 $ , 2 $ , from Station 233, 185 fathoms. 



3 ? , 6 S, from Station 235, 370-419 fathoms. 



2 ? , 1 S, from Station L66, 133 fathoms. 



