NEMATOBRACHION. 265 



third, rather abruptly bent upwards, at a little distance from its base; before 

 this curvature its upper edge is produced into a flat, vertical plate and at a short 

 distance from the curvature the joint is again somewhat bent, but in the opposite 

 direction and thus directed forwards; seventh joint two thirds to three fourths 

 as long as the sixth, at the end with six closely set, long, serrate, stifif but thin 

 spines, four of these projecting from the end, two from the side a little from 

 the end. Third to fifth pairs of legs with the shape and relative length of the 

 joints in the main as in Thysanopoda. Sixth pair of legs with the full number of 

 joints in the somewhat short endopod and the exopod is well developed. Seventh 

 pair with a normally developed, sometimes small exopod, while an endopod is 

 not developed, the exopod-bearing joint terminating in a .short, broad lobe with 

 some setae. — Branchiae nearly as in Nematoscelis. — Preanal spine simple 

 in the male, simple or bifid in the female. — Luminous organs as in Thysanopoda, 

 etc. 



The copulatory organs of first pleopods in the main as in Thysanopoda, 

 with all lobes and fi\'e processes well developed. — No female with ovisacs has 

 been found. 



Remarks. — This interesting genus was founded by Dr. Caiman on a single 

 specimen of a new species; he named it Nematodactylus boopis, and correctly 

 referred Stijlocheiron flexipes Ortm. to the same genus without having seen any 

 specimen. Later Caiman obtained a little more material, among which a muti- 

 lated male, of N. boopis and then he published additions and corrections to 

 his earlier statements and changed the name of the genus to Nematobrachion, 

 as the former name was preoccupied. Caiman's account of the genus and of his 

 single species is very good, but as he has examined only one species, while I 

 possess three species, and as the interesting sexual differences in antennulae 

 and the sixth pair of thoracic legs in the other genera with tlivided eyes were 

 then nearly unknown, I ha\'e thought it useful to give here a description of 

 the genus. I must add that in 1905 I referred Stijlocheiron flexipes Ortm. to the 

 present g?nus, having overlooked that this had already been done by Caiman 

 in 1896. 



According to some remarks in 1905 Caiman has felt the difficulty as to the 

 relationships of Nematobrachion and the three other genera with divided eyes 

 and one pair of prehensile legs ; in mentioning the two posterior pairs of thoracic 

 legs he correctly pointed out their resemblance with Thysanopoda, and he states 

 that the copulatory organs of first pleopods are "much more complex" than in 

 Stj'locheiron or Nematoscelis. Nematobrachion occupies in reality a very 



