A.MPHIPODA. 275 



long spines on setae, before and behind ; 5th joint three-quarters <>!' bhe length of I he 

 3rd and 4th together. Dactvlus rather small, curved at the point (fig. 33. pp. 4 ). In 

 bhe 3rd pair the hind margin of the 1st joint is straight, in the 4th and 5th convex. 



First uropods : rami subequal, shorter than the peduncle; all spinous. 



Second uropods like the 1st, but the rami rather longer than the peduncle. 



Third uropods wanting. 



Telson cleft almost to the base, the divisions pointed with an angle on the inside. 



Length 5 millims. 



There are certain discrepancies between our specimens and Dana's description and 

 figures of the New Zealand form, as given by Sp. Bate. I attach no importance to 

 the omission of the antennular appendage, as this is small and not easy to see. But 

 if we are to take the proportions of the first 2 and last 3 pairs of perseopods shown 

 in the figure as even approximately correct, they are quite different from ours. On 

 tin' other hand, the 1st gnathopods are so peculiar and the description and figures of 

 both pairs agree so well, that I feel justified in considering them identical. The 

 species requires a new genus, but the absence of the 3rd uropods makes a satisfactory 

 definition impossible. 



Elasmopus, Costa, 1856. 



The mandibular palp in this genus is of two distinct forms; the one (A) with the 

 3rd joint slender, its hind margin straight, and its front margin rather sparsely setose 

 or naked, approaching the same appendage in Mara, e.g., 3f. obtusata (Mont.); the 

 other (B) as in E. rapax, Costa, with the 3rd joint strong, the hind margin convex 

 and the front margin pectinate. 



To (A) belong, of the species under consideration, 



E. subcarinatus (Haswell) = E. persetosus, Stebbim; 



To (B) belong the new species E. serrula, E. spinimanus, and E. dubius. 



(A) Elasmopus subcarinatus (Haswell) Plate V., figs. 34. 



Megamsera subcarinata, Haswell, 'Proc. Linn. Soc. N.S.W.,' vol. 4, p. 335, Plate XXI. 



E. subcarinata (Haswell) (E. persetosus, Stebbing), ' " Chall." Amph.,' p. 1019, Plate XCVIII. 



Abundant and occurs all round Ceylon. 



Length of adult male 7 '5 millims. 



The antennular appendage is 2-jointed instead of 6, otherwise it agrees with the 

 " Challenger" description, except in the sculpture of the hand of the 2nd gnathopods 

 of the male, which varies considerably. In the smaller specimens there is generally 

 a single flat-topped lobe near the base of the dactylus ; in the larger this is divided 

 in two by a sinus. In the largest of all there is hardly a trace of a lobe or tooth on 

 any part of the hind margin, which is densely setose in all (figs. 34. gn. 2 8 and ? ). 

 Nunc aic quite like the "Challenger" drawing. The 3rd joint of the mandibular 

 palp is distinctly longer than the 2nd. 



2 x 2 



