272 Messrs. J. Wood-Mason and A. Alcock on 
lateral outstanding spine larger than the rest. In the last 
of these legs the third joint is fixedly united to the fourth, 
the division between the two perfectly retaining its primitive 
distinctness ; in the second the union is more perfect, but the 
division may be readily made out on the inner side ; while in 
the first the union is more perfect still, and the primitive 
distinctness of the parts is scarcely traceable; so that the 
fusion of the two joints in question becomes more and more 
perfect as we pass from behind forwards until at last it is no 
longer possible to distinguish them. The compound joint is 
curved, like its predecessors in the series, to fit the convex 
ventral surface of the thorax. ‘Their terminal joint forms a 
stoutish curved and acuminately-pointed claw. There is no 
trace either of epipodites or of exopodites on any of the legs. 
The protopodites of the abdominal appendages are long, 
being more than half the length of the rami in the first pair, 
and less than half their length in the succeeding pairs. The 
apical half more or less of their carinated outer margin is 
armed with small spines, which increase in length towards 
the apex, near to which there is usually a single spine that 1s 
much larger than the rest. Near their base on the posterior 
face a transverse suture divides them into a long distal and a 
short and incomplete proximal joint. Their rami are all 
long-lanceolate and undivided membranous plates, with the 
exception of the inner ramus of the first pair; this is in’ both 
sexes only about one third the length of the outer and is 
pyriform or obclavate in outline ; flat and flexible and fringed 
with sete on both edges in the female, it appears convex and 
stiff and glabrous and somewhat subulate or acuminate in the 
male, owing to the apical half more or less of its edges being 
folded up into a sort of tube, and owing to the fringe of its 
outer margin being reduced to short and simple sete ; the outer 
ramus of the first pair is in both sexes narrower than either 
of the rami of the succeeding pairs. In the appendages of the 
second to the fifth pairs inclusively the inner ramus is shorter 
and narrower than the outer, and is furnished near its base on 
the inner side with a short cylindrical appendix cnterna, pro- 
vided at its apex with mimute hooks for attachment to its 
fellow of the opposite side. In the second pair in the male 
there arises from the imner ramus, in front of and slightly 
internal to the appendix interna, a tapering finger-shaped 
appendix maseulina, and the second joint of the protopodite 
is subdivided by a false jomt into two approximately equal 
parts. 
The rami of the sixth pair of abdominal appendages are 
firmly chitinized, rigid, oval plates, the outer almost twice the 
