n 2 CRUSTACEA MALACOSTRACA. Ill 



Length of a female with marsupium 3^9 mm., of a large female without marsupium 4-8 mm. 



Male. As usual, considerably more slender (fig. 4a) than the other sex, about five and a 

 half times as long as the breadth of first thoracic segment. — Antennulae (fig. 4 b) with second joint 

 conspicuously shorter than in the female; third joint (fig. 4c, j) in the main as in the male, but 

 fourth joint (4) much longer than in the female, longer than thick. — The antennae have their second 

 joint somewhat longer and considerably thicker than in the female, a little longer than head and first 

 thoracic segment combined; flagellum with about 13 joints. 



First thoracic segment has about three distinct tubercles in a transverse row (fig. 4 b), the 

 three following segments each with a transverse row of distinct tubercles a little from the front mar- 

 gin. Fifth thoracic segment far from cylindrical, as it tapers from both ends towards the rather narrow 

 median part; it is about five and a half times as long as broad, and nearly longer than the posterior 

 part of the body. 



Abdomen (figs. 4 a and 4 d) broader than in the female, scarcely one-third as long again as 

 broad, with the posterior part distinctly less produced than in the female and evenly rounded, while 

 the dorsal median area is scarcely as broad as one of the lateral areas. — Operculum (fig. 4 e) con- 

 spicuously longer than broad; the median lamella in its natural position tapering very moderately 

 from somewhat from the base to near the end, which overreaches the lateral plates; these are more 

 oblong (fig. 4 e) than in //. longiremis and coarsely granulate (fig. 4g); in comparing fig. 4 f, represent- 

 ing the median lamella removed from the animal, with fig. 4 e, it is perceived chat its lateral parts 

 are overlapped by the lateral plates, second pair of pleopods. — Uropods (figs. 4 a and 4 d) longer than 

 in the female, somewhat more than half as long as the abdomen. 



Length 37 mm. 



Remarks. The female of H. frigidus is easily separated from H. Sclniiidtii by the narrow 

 abdomen and other minor features; it is closely allied to H. granulatus Rich., but in the latter species 

 both sexes have the fifth thoracic segment considerably shorter in proportion to breadth at or before 

 the middle, and in proportion to the remaining posterior part of the body, than is the case in H. 

 frigidus. 



Occurrence. Taken by the "Ingolf" at six stations, all in the cold area. 



North of the Faeroes: Stat. 141 : Lat. 63°22' N., Long. 6°58' W., 679 fath., temp. -=- o-6° ; ab. 20 spec. 



.Stat. 139: Lat. 63 "36' N., Long. j°2,o' W., 702 fath., temp. -4- o-6°; ab. 20 spec. 



East of Iceland: Stat. 105: Lat. 65°34' N., Long. 7°3i' W., 762 fath., temp. -=- o-8°; 1 spec. 

 Stat. 102: Lat. 66°23' N., Long. io°26' W., 750 fath., temp. -4- 0-9°; 2 spec. 

 Stat. 101: Lat. 66°23' N., Long. i2°05' W., 537 fath., temp. -4- 07 ; 1 spec. 



North of Iceland: Stat. 124: Lat. 67°4o' N., Long. i5°40 ; W., 495 fath., temp. -4- 0'6°; 11 spec. 



Group VI. Pseudomesini. 



This group is established on a single genus (with a single species), which in general aspect 

 is somewhat similar to the Ischnomesini, but differs from it in some important characters, and on the 



