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, stiff but thin 
spines, four of these projecting fromthe 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, 
ete. 
The copulatory organs of first pleopods in the main as in Thysanopoda, 
with all lobes and five processes well developed.— No female with ovisacs has 
been found. 
Remarks.— This interesting genus was founded by Dr. Calman on a single 
specimen of a new species; he named it Nematodactylus boopis, and correctly 
referred Stylocheiron flexipes Ortm. to the same genus without having seen any 
specimen. Later Calman 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. Calman’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 divided eyes were 
then nearly unknown, I have thought it useful to give here a description of 
the genus. I must add that in 1905 I referred Stylocheiron flexipes Ortm. to the 
present genus, having overlooked that this had already been done by Calman 
in 1896. 
According to some remarks in 1905 Calman 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 
Stylocheiron or Nematoscelis. Nematobrachion occupies in reality a very 
