272 Messrs. J. Wood-Mason and A. Alcock on 



(Dana). The inner flagellum of the antennules is short and 

 but little longer than the outer, and is unmodified at base in 

 the male. The dorsal carina of the abdomen commences in 

 the second somite as a faint and blunt elevation of the ante- 

 rior half of the tergum, and is continuous and distinct from 

 the base of the third to the extremity of the last tergum, at 

 which it ends in a single minute point, being cleft so as to 

 terminate in' two points in each of the three penultimate terga. 

 In addition to the median carina the three terminal somites 

 present on each side of the middle line a tolerably distinct 

 blunt subdorsal angulation, hence appearing to be tricarinate. 



The caudal swimmerets when laid back extend much 

 beyond the apex of the telson, and the outer margin of their 

 exopodites runs out into a spine a good way from the apex of 

 the joint — primitive features which are not noticed in Spence 

 Bate's description, though the former of them is brought out 

 in the accompanying drawings of the typical form. 



Tlie largest female measures about 63 millim., the only 

 male about 51 millim., in a straight line from the apex of the 

 rostrum to that of the telson. 



One nearly mature male with four females from north of 

 Port Blair, Andaman Sea, in 112 to 244 fathoms, on 29th 

 Nov., 1888.] 



6. Metapenceus coniger, sp. n. 



Differs from the preceding in the following points : — The 

 inner flagellum of its longer antennules is fully twice as long 

 as the outer, and in the male bears at its inner and upper 

 margin near the base a short, stout, and highly indurated 

 spine of a peculiar form, the part from which the spine 

 springs being conically thickened and elevated, with its con- 

 stituent joints firmly ankylosed together. The three terminal 

 abdominal terga are much more strongly angulated sub- 

 dorsally. The omiulus ventralis of the female is built pre- 

 cisely upon the same plan as in M. jyhilipinnensis^ and 

 represents, there is little doubt, a primitive phase in the 

 evolution of the organ, though at first sight it appears to be 

 . so strikingly difierent ; its posterior moiety is a roughly 

 semicircular concave plate with prominent raised anterior 

 and lateral margins, and it abuts by its deeply bifid anterior 

 margin against the anterior moiety, which has the form of a 

 short and broad band ; its raised anterior border has an outline 

 intermediate between that of a capital T and a capital T, the 

 ends of the cross stroke of which are in the same curved line 

 with the raised lateral margins, and do not nip the sides of 



