120 CRUSTACEA MALACOSTRACA. III. 



spines on the corresponding margin of sixth joint. The most important differences between D. insignc 

 and D.plebejum are pointed out in the key. 



Occurrence. Taken by the "Ingolf" at a deep station in the warm area. 



Davis Strait: Stat. 36: Lat 6i5o' N., Long. 562i' W., 1435 fatn -t temp. 1-5; 6 spec. (3?, 3 c?). 



77. Desmosoma plebejum n. sp. 

 (PI. XI, figs. 6 a-6 d). 



Female. The upper surface of the body without distinct lineal reticulation. - Head moder- 

 ately small. - First thoracic segment shorter than the second, which is distinctly shorter than the 

 fourth. Fifth segment conspicuously narrower at the anterior than at the posterior end, with the 

 lateral margins somewhat diverging backwards and scarcely concave; the segment is not one-third 

 as broad again as the length of its median line. Epimera of first segment (fig. 6 a) anteriorly pro- 

 duced as a small, subtriangular process terminating in a distinct spine; the three other pairs of epimera 

 have their anterior halves rounded in front. 



First pair of legs (fig. 6 b) very robust. Second to fourth joints thicker than in D. insigne. 

 Fifth joint very thick, with the distal lower part produced as a foot for the very long and robust 

 spine, while its lower margin, which is scarcely half as long again as the depth of the joint, is straight 

 and without spines, but with a seta at the terminal spine. Sixth joint proportionately considerably 

 larger than in D. insignc, considerably longer than the lower margin of fifth joint, and conspicuously 

 less than three times as long as deep. - - (Second pair lost in my animals). Seventh pair (fig. 6c) 

 somewhat strong; fifth joint rather broad, with five setae on the lower margin. 



Abdomen (fig. 6 a) somewhat longer than broad, ovate, without postero-lateral teeth. - - Oper- 

 culum small, scarcely half as long as the abdomen, about as broad as long, with the posterior margin 

 rounded. - - Uropods (fig. 6 d) inserted far from the median line, small, not one-third as long as the 

 abdomen; peduncle oblong, about half as long as, and little broader than, the endopod; exopod wanting. 



Length of a female with marsupium 1-65 mm. 



Remarks. This small species is allied to D. insignc, but easily distinguished by several cha- 

 racters, some of them pointed out in the key (p. 109). It is in all probability confined to the cold area. 



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



East of Iceland: Stat. 102: Lat. 6623' N., Long. io26' W., 750 fath., temp. -=- 0-9; 2 spec. 



North-East of Iceland: Stat. 120: Lat 6729' N., Long. n32 f W., 885 fath., temp, -f- ro; i spec. 



Group X. Ilyarachnini. 



Body moderately oblong or somewhat broad and thick. Head free and broad in proportion 

 to length, without front area. Eyes wanting. Antennulae terminal; first joint plate-shaped; flagellum 

 frequently with several joints. Antennae longer than the body, .as the two distal joints of the pe- 

 duncle are very elongate, and the flagellum has numerous joints; squama feebly developed or indi- 



