NO. 1876. ON THE CRUSTACEAN ORDER CVMACEA—CALMAN. 667 



Except for one character it would, I believe, be impossible to 

 exclude the species described below from the genus Diastylis. That 

 character, the structure of the apex of the telson, is, however, one 

 that infringes the current definition of the family Diastylidse, and 

 on this account it seems advisable to distinguish the s])ecies by a 

 generic name from the assemblage of unclassified Diastylidse that 

 form the genus Diastylis. 



It is to be noted that the simply pointed apex of the telson shows 

 no trace of the coalescence of a median apical spine like that of 

 Pseudodiastylis. From that genus the present species differs widely 

 in most of its characters. 



Type-species. — Oxyurostylis smithi, new species. 



OXYUROSTYLIS SMITHI, new species. 



Immature female. — Total length, 6.6 ram. 



Carapace rather less than one-third of total length, its depth 

 less, and its width slightly more than two-thirds of its length. The 

 dorsal edge, as seen from the side, is arched posteriorly, sloping in 



Fig. 91. — OxYURosTyLi."? smithi, immature female, from the side. 



front to the short horizontal pseudorostrum. There is no antennal 

 notch and the antero-lateral angle is hardly indicated. On each 

 side of the carapace are two parallel oblique ridges uniting with 

 each other on the lower edge while their upper ends are connected 

 by a short longitudinal ridge forming one side of the depressed 

 "cardiac" area; in front of these is a short sinuous ridge passing 

 forward on to the side of the pseudorostrum; on the dorsal surface, 

 the frontal lobe is crossed by two prominent transverse ridges and 

 two others, much fainter, behind these. The ocular lobe is broader 

 than long and about half as long as the line of junction of the lateral 

 plates of the pseudorostrum; there is no ocular pigment and the 

 visual elements are indistinct. 



All the leg-bearing somites are distinct ; the postero-laterai comers 

 of the last thoracic somite are very slightly produced and bluntly 

 pointed. 



The abdomen, including the telson, is longer by about one-sixth 

 than the cephalo thoracic region and the last somite is a little shorter 

 than the preceding. The telson is about one and one-half times 



