226 DE. C. CHILTON OX THE SUBTEEEANEAN 



indicated by S. I. Smith in his figure of Cerapus tuhularis, bnt not, he thinks, alluded 

 to by any other writers. It is but just to Humbert to mention that he had drawn and 

 described the "coupling-spines" ("deux petits crochets") oi Niphargus puieanus, Yar. 

 Forelii, in 1876 [62, p. 350]. 



The second pleopod (fig. 25) has the peduncle considerably longer and broader than 

 in the first, the basal part of it being pretty distinctly marked off as a separate joint, 

 probably representing the coxa. The outer margin bears four small spines on the distal 

 half, the inner margin having only the coupling-spines at the extremity. The branch 

 is only as long as the peduncle and contains only six joints, of which the first is much 

 the largest. 



The third pleopod (fig. 26) is similar to the second, but smaller and more reduced; 

 the peduncle is similar, but narrowed at the base ; the branch is not so long as the 

 j^eduncle, and consists of three joints only, the first being much larger than the other 

 two together. 



The tirojwda are all short and rather stout. The first uropod (fig. 27) has the 

 peduncle much longer than the rami, stout, broad above, the upper surface being 

 somewhat concave, its outer margin bearing seven small spines ; the outer ramus is 

 slightly smaller than the inner, both falciform, curving upwards, the lower surface of 

 each regularly curved and with seta?, the upper surface with three or four small spines 

 near the base and one near the apex. 



The second uropod (fig. 28) is similar to the first, but shorter and bearing fewer setae. 



The third uropod (fig. 29) has the peduncle short, witli two spines on the lower 

 margin at the extremity ; the inner ramus very small, rudimentary, with a small spine 

 at the end ; outer ramus about three times as long as the peduncle, gradually tapering, 

 the upper margin with eight seta? arranged in four jiairs in a longitudinal row, the 

 extremity separated from the other portion and forming a small second joint. 



The telson (fig. 30) reaches about halfway to the end of the last uropod. It is 

 more or less oblong, narrowing slightly towards the end, which bears a stout spine in 

 a slight emargination at each corner ; the sides are slightly convex and the extremity 

 between the two spines is either straight or slightly concave. There is no sign whatever 

 of any cleft or division. 



Genus Gammakus, Fabricius, 1775. 

 (See Stebbing's Report on the 'Challenger^ Ampbipoda, p. 1005.) 



Full information on this very old genus will be found in Stebbing's Keport as quoted 

 above. In it he quotes the following generic diagnosis as having been given by Boeck 

 in 1876 :— 



" Mandibles with the third joint of the palpi elongate, narrow. 



" First maxilla; with the inner plate broad, long, furnished on the inner margin with 

 very many plumose seta?. 



" The body not carinate. The three hinder segments of the pleon furnished in the 

 middle with fascicles of spines. The anterior side-plates of moderate size. 



