6 T. V. HODGSON. 
$ 
Second pair of antennee composed of five joints in both sexes. 
Cephalon of the male large at the base, and prolonged anteriorly to a narrow 
extremity. 
Cephalon united to the first thoracic segment, leaving six segments well 
developed. 
Uropoda biramous, each branch composed of two joints. 
The first gnathopods are dissimilar in the two sexes. In the male they are 
much enlarged, and the propodite is furnished with a process directed 
backwards, a thumb, which forms a chelate hand. 
This genus has been instituted for the reception of Paratanais dimorphus 
Beddard (1), and P. antareticus Hodgson (7), which, on account of their strongly 
marked sexual dimorphism, a character they share with Heterotanais G. O. Sars, and 
other minor features, can no longer be included in any existing genus. 
NoroTANAIS ANTARCTICUS. 
Paratanais antarcticus Hodgson (8), pp. 240 & 241. 
Nototanais antarcticus Richardson (12), pp. 2 & 8. 
Body rather slender, but differing in its proportions in the two sexes, being rather 
longer in the female, notwithstanding the fact that the cephalosome is much longer in 
the male than in the female. 
Male.—The cephalosome is pyriform, long, narrowest anteriorly ; this border being 
obtusely angulated, and having a well-marked conical projection laterally which is 
occupied by the eye. This cephalosome is a little longer than the first four free 
segments of the mesosome. 
The mesosome comprises six segments; the first is very short, and the next three 
progressively increase in length, the two following decrease, the last being nearly as 
long as the third. 
The metasome is six-jointed, five of the segments being subequal in size, the last 
is twice as long and rounded, bearing the biramous uropoda postero-laterally. 
Fremale.—The cephalosome is shorter and more distinctly conical than pyriform, 
and is not longer than the first three free thoracic segments. The proportions of these 
segments are similar to those of the male, though they are longer, the length of the 
mesosome in male and female being as 9 to 11. 
First antenna. That of the male comprises five joints, of which the first is longer 
than the other four together, the proportion being as 6 to 4; the second is as long as 
the two terminal ones, the third being by a very little the shortest of the series. 
Except the penultimate all the joints bear a few long sete distally ; the terminal joint 
has half-a-dozen or thereabouts. In the female this organ is tri-articulate, the first 
joint being nearly twice the length of the other two together. There are a few long 
setee distally and in the middle of the first joint. 
