CRUSTACEA MALACOSTRACA. III. 



I05 



Occurrence. Captured by the "Ingolf" at a single station in the cold area. 



South of Jan May en; Stat. 113: Lat. 69°3i' N., Long. 7°o6' W., 1309 fath.. temp. -=- ro°; 1 spec. 



66. Nannoniscus affinis n. sp. 



(PL X, figs. 3 a— 3 c). 



Female (without marsupium). Closel)- allied to N. spinicornis and agreeing with it in most 

 features, above all in the antennulse, the shape of the antennal squama, and the anterior thoracic seg- 

 ments, thus in important characters separating N. spinicornis and N. affinis from all other northern 

 species. It is in reality sufficient to point out the three or four differences between N. affinis and 

 N. spinicornis. 



The keels on the head as in X. spinicornis without anteriorly protruding ends, and continued 

 in the convex anterior margin of the front area (fig. 3 a), but the keels converge considerably forwards, 

 so that the anterior margin of the area is much shorter than in N. spinicornis, being between one- 

 third and one-fourth of the breadth of the head. — The ventral process on seventh thoracic segment 

 (fig. 3 c) is much longer and stronger than in N. spinicornis. Thoracic legs — first pair lost — in the 

 main as in N. spinicornis, but the angle of fourth joint (fig. 3 b) terminates in a long, very strong, spini- 

 form seta almost as long as the joint. — Operculum (fig. 3 c) almost half as long again as broad, post- 

 eriori}' conspicuously more produced than in N. spinicornis, and terminating in a somewhat small, nearly 

 spiniform median process. 



Length of the largest specimen scarcely 1/3 mm. 



Remarks. It was only after some hesitation that I established A', affinis as a species. I think, 

 however, that the differences pointed out between it and the preceding form will prove to be valid 

 specific characters ; furthermore N. affinis was secured at a pronounced warm-water station, while N. 

 spinicornis was gathered at one of the deepest and most typical cold-water stations. 



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



South-West of Iceland: Stat. 78: Lat. 6o°37' N., Long. 27°52' W., 799 fath.; temp. 4-5°; 2 1 2 spec, 

 (mutilated). 



Group IX. Desmosomatini. 



Body very oblong, moderately depressed. Head free; eyes wanting. Antenuulae dorsal, short, 

 with very few joints in the flagellum. Antennae moderately long, thicker in the males than in the 

 females; squama not perceptible. Mandibles with the incisive part, the movable lacinia, and the setae 

 well or very moderately developed; the molar process reduced, rather short or short, tapering to the 

 narrow, setiferous end, and directed somewhat backwards; palp 3-jointed or wanting. Palp of the 

 maxillipeds nearly as in Naunoniscini; epipod somewhat long. — Thoracic segments movable, divided 

 into two very different sections. The four anterior pairs of thoracic legs inserted on the sides of the 

 segments, and at least second to fourth pairs with well developed epimera; first pair very different 



The Fngolf-Expedition. III. ;. '4 



