IlS CRUSTACEA MALACOSTRACA. III. 



75. Desmosoma armatum G. O. Sars. 

 (PL XI, fig. 4 a). 



1864. Desmosoma ay mat am G. O. Sars, Forh. Vid. Selsk. Christiania for 1863, p. 216. 

 ! 1897. G. O. Sars, Account, II, p. 126; PL 54, fig. 2. 



The representation published by Sars is on the whole good, and quite sufficient for the recog- 

 nition of the species. The shape of fifth and sixth joints in first and second pairs of legs and their 

 equipment with spines and setae afford good characters. Only a few features may be mentioned as 

 additions or corrections. 



The epimera of first thoracic segment are somewhat produced anteriorly, with the free inner 

 or rather anterior margin concave, and the narrow end terminating in a robust, somewhat short spine. 

 The epimera of second and third segments are slightly or scarcely produced forwards, but anteriorly 

 angular with a minute hair. In my specimen and in a co-type of Sars I have found the seventh pair 

 of legs (fig. 4 a) less slender than figured by that author; fifth joint has five setae on the lower margin, 

 three or four of them very long, and this joint has, besides, near the upper margin, five long hairs; 

 sixth joint has four setae on the lower margin, three of them long, and some seta; at or near the 

 upper margin. 



Length of the specimen from Greenland, a female with marsupium, 175 mm. 



Remarks. In having no exopod on the uropods D. armatum agrees with the two following 

 species, but differs strongly from both in the shape and spines of fifth joint of first pair of legs. As 

 to spines and setae on fifth and sixth joints of first and second pairs of legs, D. armatum is inter- 

 mediate between D.politum and D. coarctation, but it differs from both these forms and from D. uatator 

 in having no exopod on the uropods. 



Occurrence. It has not been taken by the "Ingolf"; but in 1891 by the Ryder Expedition at 

 the following place. 



East Greenland: Danmark O, Lat. 70°27' N. ; 1 spec. (% with marsupium). 



76. Desmosoma insigne u. sp. 

 (PI. XI, figs. 5 a- 5 g). 



Female aud Male. In the female the major part of the upper surface of the body seems to 

 be reticulated, in reality set with a large number of partly long, extremely fine, sharp keels; these 

 keels are mainly transverse on the middle of the head, on second to fourth segments, and on the 

 posterior median part of the other segments, longitudinal on the head and on the more lateral parts 

 of fifth (fig. 5 b) to seventh segment. In the male this adornment is much less developed, has vanished 

 on large areas (fig. 5 c). 



The head is somewhat narrow (fig. 5 a); the antennae in the female rather short, in the male 

 proportionately longer and much thickened. — First thoracic segment longer and a little narrower 

 than the second, but about as long as the fourth. Fifth segment in the female (figs. 5 a and 5 b) 

 broader than the preceding segments, slightly more than twice as broad as long in the median line, 

 with the anterior margin somewhat concave, the lateral margins anteriorly convex, and near the middle 



