7Q CRUSTACEA MALACOSTRACA. III. 



Abdomen (fig. 3 d) about one-third as long again as broad; the part between the uropods con- 

 siderably produced, with the median part of its posterior margin very feebly rounded, almost transverse. 



Operculum (fig. 3 e) conspicuously longer than broad, with the posterior margin moderately long 



and slightly convex. — Uropods nearly straight, acute, a little less than half as long as the abdomen. 



Length of the single specimen 4.2 mm. 



Remarks. H. Schmidtii is easily separated from the female of H. longiremis by having fifth 

 thoracic segment much shorter and thicker, and by a more oblong operculum ; from H. frigidus it is 

 instantly distinguished by having the abdomen conspicuously broader and another shape of the oper- 

 culum. According to my own examination of three specimens of //. Greeni Tatt. kiudly lent me by 

 Dr. Tattersall, this species differs from H. Schmidtii in several particulars: the three distal joints of 

 the antennulse are several times longer than in H. Schmidtii, the first thoracic segment has at least 

 frequently its antero-lateral angles produced into conspicuous conical processes directed mainly for- 

 wards, the spiniform granules on the anterior segments and on second joint of the legs are consider- 

 ably longer and consequently more conspicuous than in my species, finally the inner distal angle of 

 third antennal joint is produced into a conspicuous small process or tubercle terminating in a minute 

 spine — a feature not observed or drawn by Tattersall — and, besides, this third joint has at the 

 middle of the proximal half of its lower or inner margin an oblong, spiniform process directed for- 

 wards and downwards, and figured by Dr. Tattersall. Besides, I have compared co-types of H. spines- 

 cens Rich, and H. granulatus Rich, kindly lent me by the authorities of the U. S. National Museum. 

 H. spinescens — the largest specimen, a female without marsupium, was 57 mm. long — differs from 

 H. Schmidtii especially in having the end of third antennal joint produced in an acute process, while 

 the fifth thoracic segment in the female is distinctly longer in proportion to its narrowest breadth 

 than in H. Schmidtii, and nearly or fully as long as the posterior part of the body. (It may be inserted 

 here that H. spinescens Rich, differs from H. Greeni Tatt. especially in having the distal part of the 

 antennulse shorter and only two-jointed, in having no proximal process on third antennal joint and 

 the surface of the anterior segments less scabrous). The female of H. granulatus — ovigerous 

 females were 3-9 and 3-3 mm. long — is easily distinguished from H. Schmidtii in being more clumsy, 

 with fifth thoracic segment conspicuously shorter, only a little more than half as long again as broad 

 across its most narrow part, and only as long as the abdomen, furthermore in having the abdomen 

 narrower than in H. Schmidtii and shaped nearly as in H. frigidus, the uropods less than one-third 

 as long as the abdomen, etc. 



The species is named in honour of Dr. Joh. Schmidt, who, during his cruizes in the "Thor", 

 collected a good number of the Isopoda described or enumerated in the present report. 



Occurrence. Not taken by the "Ingolf". But the "Thor" has secured it at a single place 

 in the warm area. 



South of Iceland: Lat. 62 c 57' N., Long, ic/^' W., 508 fath.; 1 spec. 



