220 Transactions. 



Art. XXV. — Some New Zealand Amphipoda : No. 2* 



By Charles Chilton, M.A., D.Sc. M.B., CM., LL.D., F.L.S., C.M.Z.S., 

 F.N.Z.Inst., Hon. Mem. Roy. Soc. N.S.W. ; Professor of Biology, 

 Canterbury College, N.Z. 



[Bead before the Philosophical Institute of Canterbury, 3rd November, 1920 ; received 

 by Editor, 31st December, 1920 ; issued separately, 20th July, 1921.] 



Apherusa translucens (Chilton). (Fig. 1, A to K.) 



Panoploea translucens Chilton, 1884, p. 263, pi. 21. fig. 3 a-c. 

 Apherusa translucens Stebbing, 1906, p. 308. 



This species was described from three specimens taken in 1884 in Lyttelton 

 Harbour, but, as the description was based on the female only, the species 

 has remained somewhat obscure. It was at first placed under the genus 

 Panoploea G. M. Thomson, owing to its supposed resemblance to P. debilis 

 G. M. Thomson. This species, however, has proved to be identical with 

 Pherusa novae-zealandiae G. M. T., and has been placed by Stebbing in 

 the genus Leptamphopus. The genus Panoploea has been retained for the 

 other species described by Thomson, P. spinosa, which belongs to another 

 family. The species described as Panoploea translucens was thus left 

 without a genus, and Stebbing has assigned it to the genus Apherusa 

 A. Walker. This genus seems somewhat ill-defined and without well-marked 

 characteristics, but so far as they go the characters of the species now under 

 consideration agree with those of the genus. Apherusa translucens seems 

 to be somewhat rare in New Zealand, and 1 have very few specimens, and 

 all of these somewhat imperfect. Among them, however, is a male, and 

 I am therefore now about to give the characters of this sex and an 

 amended description of the species, as follows : — 



Body smooth, back without any dorsal teeth. Head without rostrum. 

 Pleon segment 3 with postero-lateral angle scarcely produced, posterior 

 margin smooth, straight or slightly convex, except above angle where it 

 is slightly concave, inferior margin with 5 spinules. Eye large, oval. 

 Gnathopods 1 and 2 similar in structure, those of the male considerably 

 stouter than those of the female, the first in each sex slightly larger than 

 the second. In the male the first gnathopod with propod widest at the 

 beginning of the palm, rather more than half as broad as long, anterior 

 margin straight, palm about as long as the hind-margin, regularly convex 

 and fringed with rows of setules but without special defining spine ; hind- 

 margin with 5 or 6 small tufts of fine setules. In the female the basal 

 joint of first gnathopod showing a constriction about one-third its length 

 from the base, remaining joints much more slender than in the male. 



* For No. 1 of this series see Trans. N.Z. Inst., vol. 52, pp. 1-8, 1920. 



