CRUSTACEA MALACOSTRACA. III. 71 



44. Heteromesus frigidus 11. sp. 

 (PL VI, figs. 4 a- 4 t). 



Female. Body still a little more robust than in H. Sc/i/itidfii, only about four and a half 

 times as long as the breadth of first thoracic segment. The surface of the body and legs as to granu- 

 lation and distribution of wavy markings or impressions (fig. 4}) on the thoracic segments nearly as 

 in the preceding form. 



Antennulie (figs. 4i, 4 k and 4 1) still more reduced than in H. Schmidtii. Second joint about 

 half as long as head and first thoracic segment combined; at its upper distal angle is found a minute 

 impression, in which is seen a tiny knot frequently difficult to examine; in reality this knot consists 

 of two joints, the first (fig. 4 1, j) more than twice as broad as high, with a couple of fine setae on 

 the margin, the second joint (4) exceedingly tiny, with a fine seta and a proportionately very long 

 and strong seta on the upper surface. -- The antennae nearly reach the posterior end of fifth thoracic 

 segment; third joint is scabrous, closely set with minute, sharp granules, it is about as long as the 

 head or as sixth joint, its end is rounded without any process, and it has no proximal process at the 

 lower margin; flagellum about as long as the two distal peduncular joints combined, with about 14 

 joints. — The labrum has each antero-lateral angle produced into a small, but conspicuous tooth. 



First thoracic segment (fig. 4 i) with each antero-lateral angle produced into a more or less 

 conspicuous triangular tooth ; sometimes a minute tubercle may also be found on the side of second 

 segment, but the four anterior segments have in this sex no transverse row of small tubercles. Fifth 

 segment is from a little more to slightly less than twice as long as broad at its most narrow point, 

 and somewhat shorter than the posterior part of the body, being about as long as the abdomen plus 

 seventh thoracic segment. 



First pair of thoracic legs (figs. 4 p and 4 q) robust; fifth joint only one-third as long again as 

 deep, with the usual long and very strong spine a little before the end of the lower margin and a 

 similar spine on the lower end of the long, oblique terminal margin; the last-named margin has, 

 besides, (fig. 4 q) two short, very thick spines, each with a seta near the middle, and a low plate with 

 the margin serrate; sixth joint about as long as the fifth, almost twice as long as deep, with both 

 margins considerably convex, and the lower margin has beyond the middle a couple of short, thick 

 spines, each with a seta at the middle; seventh joint with claw somewhat robust, as long as the lower 

 margin of sixth joint. The other six pairs of legs nearly as in H. Schmidtii, with second joint scabrous; 

 the end of second joint of fourth pair, when directed backwards, reaches somewhat beyond the end of 

 the corresponding joint of fifth pair stretched forwards. 



Abdomen (figs. 4h and 4 r) narrow, half as long again as broad; the longitudinal median area 

 on the surface is conspicuously broader in proportion to the lateral areas than in any other of my 

 species; the part between the uropods is much produced, with the terminal margin very flatly convex. 

 — Operculum (figs. 4 s and 4 t) somewhat longer than broad; its major part is circular, while a broad 

 anterior part is produced forwards, so that the lateral margins somewhat from the base are sharply 

 concave or rather bent inwards. — Uropods generally feebly curved, somewhat less than half as long 

 as the abdomen. 



