38 



wholly absent, in male normally developed. Uropoda imperfectly biramous, the 

 outer ramus not being defined from the basal part. 



Remarks. — In this genus also, the structure of the metasome in the 

 female yields the most conspicuous distinctive, character; but whereas in the 

 genus Strongylura this division is of quite an unusual size, it is in the present 

 genus more reduced in size than in any hitherto known Tanaid. In the male, 

 however, this part exhibits quite a normal appearance. The structure of the 

 chelipeds is likewise somewhat peculiar and differs, among other things, from 

 that of all other Tanaids in the form of the basal part. The oral parts, and 

 especially the mandibles, exhibit a similar rudimentary condition to that found 

 in the genus Tanaopsis. Besides the typical species described below, the Austra- 

 lian form Paratanais linearis Haswell, according to the opinion of the Rev. Mr. 

 Stebbing, should more properly be referred to this genus. 



Anarthrura simplex, G. 0. Sars. 



(PI. XVI, fig. 2). 

 Anarthrura simplex, Q. 0. Sars, 1. c. p. 54. 



Specific Characters. — Body in female about 8 times as long as it is 

 broad, in male somewhat shorter, segments marked off by rather deep constrictions. 

 Cephalosome distinctly depressed, scarcely longer than it is broad, and obtusely 

 truncated in front. 1st and last segments of mesosome shorter than the others, 

 and almost quadrate in outline. Metasome in female scarcely longer than the 

 penultimate segment of mesosome, narrow cylindric, or very slightly depressed, 

 and somewhat constricted in the middle, tip obtusely angular; that in male nearly 

 twice as large, and of altogether normal appearance. Superior antenna? in female 

 about the length of the cephalosome, basal joint but little longer than the 2 

 succeeding ones combined, terminal joint narrow, conical in form. Chelipeds with 

 the basal part occupying half their length, and having its first segment much 

 larger than the 2nd, hand longer than the carpus, but rather feeble, with the 

 palm unusually short, fingers narrow and not perfectly contiguous when shut, the 

 movable one slightly serrated outside, the immovable one nearly straight and termin- 

 ating in a lanceolate point. The 3 anterior pairs of pereiopoda exactly alike, having 

 the propodal joint tapering conically, and the dactylus long and setiform; the 3 

 posterior pairs more strongly built, with the basal joint rather tumefied, and 

 the dactylus quite short. Uropoda generally turned obliquely outwards, inner 

 ramus well defined, biarticulate, outer represented by a conical, setiferous pro- 

 jection of the basal part. Length of female 2.35 mm. 



