CRUSTACEA MALACOSTRACA. Ill lx - 



Abdomen (figs. 8 a and 8 e) a little longer than broad; the lateral margins converge somewhat 

 backwards to the postero-lateral teeth, which are small, directed mainly backwards and placed consider- 

 ably before the end of abdomen, as the posterior margin is very convex. — Uropods somewhat less 

 than half as long as abdomen, rather distant from the median line; peduncle somewhat thicker than 

 the eudopod; exopod minute, very thin and only about as long as the diameter of the endopod. 



Length of a large female without marsupium T2 mm. 



Remarks. D. politum is allied to D. coarctation (Hansen, MS.) G. O. Sars, but the latter is 

 separated from it by a very different shape of fifth thoracic segment, and in having only three spines 

 on the lower margin and no spine on the terminal margin of fifth joint of first pair of legs. D. poli- 

 tum is, besides, closely allied to D. armatum G O. Sars, which, however, differs from it especially in 

 having the first pair of epimera produced into somewhat long, oblong-triangular, acute processes, in 

 having no exopod on the uropods, and in some further particulars. 



A very small specimen (from Stat. 90) with seventh pair of legs still wanting shows the curious 

 feature that fifth joint of first pair of legs possesses only the long spine on the distal lower angle and 

 no further spine at the lower margin, thereby being rather similar to the same joint in D. insigne 

 n. sp. and D. plcbejum n. sp. But it is instantly separated from these species in having the distal lower 

 angle of the joint mentioned broadly rounded, while in the two species named this angle is produced 

 as a kind of foot for the very long spine. 



Occurrence. Taken by the "Ingolf" at two stations in the warm area. 



West of Iceland: Stat. 90: Lat. 64°45' N., Long. 29°o6' W., 568 rath., temp. 4-4°; 9 spec. 



South-West of Iceland: Stat. 78: Lat. 6o°37' N., Long. 2-j°^2' W., 799 fath., temp. 4-5°; 3 spec. (1 



very young). 



73. Desmosoma natator n. sp. 

 (PL XI, figs. 2 a— 2 e). 



Male. The upper surface of the body reticulate, nearly looking as if covered with very small, 

 more or less rounded scales set close together but never overlapping each other. — Head large, long 

 and broad. First thoracic segment broader and a little longer than the second, but scarcely as long 

 as the fourth. All epimera have their anterior section produced forwards and outwards into very con- 

 spicuous, though moderately short, triangular processes, decreasing a little in length from first to fourth 

 pair; the two anterior pairs are nearly as long as broad, and all pairs have the narrow end terminating 

 in a small but very distinct spine. Fifth segment anteriorly considerably broader than long, with the 

 front margin straight and long, the lateral margins considerably concave, the anterior angles produced 

 outwards, and their narrow end terminating in an outstanding spine. 



First pair of legs (fig. 2 b) very robust; fourth joint on the upper distal angle with two very 

 stiff setae or thin spines, and one of them nearly as long as the next joint. Fifth joint not fully twice 

 as long as deep; its lower margin and end with four spines in all; the spine on the distal angle long, 

 though a good deal shorter than sixth joint; the spine just above the angle and the two other more 

 proximal spines moderately long. Sixth joint scarcely shorter than the fifth, not quite two and a half 

 times as long as deep. — Second pair of legs robust (fig. 2 c); fiftli joint three times as long as deep, 



15* 



