222 Transactions. 



Gnathopod 2 similar to the first in both sexes, but slightly smaller and 

 with basal joint straight. Basal joint of peraeopoda 3-5 moderately 

 expanded, oval, posterior margin with minute shallow crenations or ser- 

 rations. Uropods 1 and 2 slender, similar, the outer ramus much shorter 

 than the inner, inner margin of each ramus fringed with very minute 

 spinules. Uropod 3 stouter and shorter, branches broadly lanceolate, 

 about as long as peduncle. Telson oval, narrowing posteriorly, margin 

 entire or with one or two minute setules on each side of the apex. 



Length, about 9 mm. 



Locality . — Ly tt elton Harbo ui . 



This species shows considerable resemblance both to A. cirrus (Bate) 

 and to A. jurinei (M.-Edw.). If differs from the first in having no dorsal 

 teeth, in this respect agreeing with A. jurinei, but the shape of the third 

 pleon segment agrees closely with that of A. cirrus, thus differing from 

 A. jurinei. The telson agrees closely with that of A. jurinei. In neither of 

 these species does Stebbing speak of any sexual differences in the gnatho- 

 poda. Walker (1912, p 600) has drawn attention to the variation in the 

 shape of the third pleon segment in A. jurinei, and to sexual differences in 

 the antennae in that species. Unfortunately the antennae are wanting 

 in my specimens of A. translucens, and I am therefore unable to say 

 whether similar differences are to be found in it. 



Apherusa levis (G. M. Thomson). (Fig. 2, A to F.) 



Amphithonotus levis G. M. Thomson, 1879, p. 330, pi. 16, figs. 1-4 ; 

 188L p. 215. pi. vii, fig. 6: Thomson and Chilton, 1886. p. 148: 

 Stebbing, 1906, p. 741. 



This species was described by G. M. Thomson in 1879, and was referred 

 to the genus Amphithonotus as agreeing well with the generic characters 

 given by Spence Bate in the Catalogue of the Amphipoda of the British 

 Museum. It appears, however, that the species at that time referred to 

 Amphithonotus really belong to other genera, and the genus therefore 

 lapsed. I have had some difficulty in deciding which is the proper genus 

 to which Mr. Thomson's species should be referred, but its resemblance 

 in nearly all points to the preceding species, Apherusa translucens, is so 

 close that I am putting it down to the same genus. The only point in 

 which it differs from Stebbing's description of the genus (1906, p. 304) is 

 that the telson is distinctly cleft posteriorly, though not deeply so, while 

 he describes the telson as being " entire." I presume, however, this 

 means ' ; simple " — that is, not divided — and the telson of the present 

 species could quite well come under this description. Moreover, some of 

 the species which he ascribes to Apherusa have the telson distinctly 

 toothed or serrate posteriorly, and the margin therefore not entire. 



Apherusa levis agrees with A. translucens in having the first and second 

 gnathopods in each sex similar, the first being very slightly larger than 

 the second, and both pairs in the male being considerably larger than 

 corresponding pairs in the female. It differs, however, in the presence 

 of a well-marked rostrum and in the shape of the telson ; there are also 

 slight differences in the gnathopods. It may be re-defined as follows : — 



Body quite smooth, without dorsal teeth. Cephalon produced into a 

 distinct rostrum. Eye large, oval with anterior margin straight or slightly 



