15 



anteriorly, and the branchial regions are sHghtly swollen. The rostrum is prominent, the lateral 

 plates meeting in front of the cephalic lobe for nearly one quarter of the total length of the 

 carapace. Its dorsal surface slopes a little downwards and the tip is truncate as seen from 

 above, rounded below as seen from the side. There is no distinct antennal notch and the very 

 short antero-lateral margin of the carapace meets the lower margin nearly at right ancrles. The 

 eyes are set near together and are very large and darkly pigmented, each with three laro-e 

 corneal lenses. The surface of the carapace is smooth, without tubercles or teeth and without 

 any conspicuous hairs. 



The five leg-bearing thoracic somites are all distinct. The pleural plates of all except 

 the first are expanded laterally. The abdomen is a little less than three-fourths of the length 

 of the cephalothoracic region and its somites have well-marked lateral grooves. 



The appendages, so far as examined, are closely similar to those of H. longirostris with 

 the exception of the first legs (text-fig. ic) which are very stout. The propodus is hardly 

 narrower than the carpus and the dactylus is less than one third of the length of the propodus 

 and bears a very short stout curved claw. 



The uropods (text-fig. 3£j.) have the peduncle two and a half times the length of the 

 last somite and little more than one and a half times the length of the endopod. The latter 

 carries seven spines on its inner edge and has a short terminal spine. The e.xopod is broken 

 on both .sides of the single specimen. 



Occurrence. Station 37. Plankton. One specimen. 



Remarks. This species is allied to N. longirostris Sars, but is at once distinguished 

 from that species by the much shorter pseudorostrum and by the very different structure of 

 the first pair of legs. N. hirsutus Hansen, (Isop. Cumac. Plankton Exp. 1895, p. 59, pi. Ill, 

 figs- 3, 3^), is also allied but is distinguished by the hairy and much deeper carapace, shorter 

 pseudorostrum, shorter uropods, slender first legs and other characters. The three species 

 together stand somewhat apart from the other numbers of the genus and may perhaps be 

 found to deserve generic separation. 



Nannastacus spp. 



Specimens of this genus, belonging to several probably new species which, for reasons 

 given above cannot at present be described, occurred at Stations 37, 40, 142 and 164. 



Cumella. 



Cumella spp. 



The remarks made above as to the genus N'annastactis apply with equal force to the present 

 genus, and I therefore refrain for the present from describing five male specimens representing 

 apparently two new species, obtained at stations 37, 40 and 41. 



