NO. 18T6. ON THE CRUSTACEAN ORDER CUMACEA—CALMAN. 



64 1 



DIASTYLIS ASPERA, new species. 



Ovigerous female. — Total length, 12.2 mm. 



Carapace inflated, less than one-thu-d of total length, its height a 

 little more than two-thirds and its width five-sixths of its length. A 

 very oblique (nearly horizontal) ridge on each side runs on to the side 

 of the pseudorostrum; a little way behind the ocular lobe it is jomed 

 by a curved ridge running up from the lower edge of the carapace. 

 The latter ridge also receives the lower end of an oblique ridge 



The antero- 



FlG. 66.— DiASTYLIS ASPERA, FEMALE, FROM THE SIDE. 



forming an angle with the first and, like a much fainter parallel ridge 

 just behmdit, passing at its upper end into a prominent dorsal longi- 

 tudinal ridge, which, with its fellow, bounds the deeply hollowed car- 

 diac region. There are several other minor ridges on the surface of 

 the carapace, the most conspicuous bemg two transverse folds crossing 

 the fi'ontal lobe belimd the slightly prominent ocular lobe. The whole 

 surface is rough with small spiniform points becoming larger anteriorly 

 and arranged in rows along the more prominent ridges. The pseudo- 

 rostrum is of moderate length, horizontal, and acute, 

 lateral angle is hardly indicated. The ocular lobe is 

 broader than long and its corneal areas are obscure. 



The pleural expansions of the second free thoracic 

 somite are small and rounded anteriorly. The dorsal 

 surface of all the somites is smooth, but the anterior 

 margms of first, second, and fifth are finely serrate. 

 The postero-lateral angles of the fifth somite are 

 rounded. 



The length of the abdomen, including the telson, is 

 slightly greater than that of the cephalothoracic 

 region. The first somite has a pair of small dorso- 

 lateral teeth; the posterior somites have a group of granules and some 

 shallow depressions on each side, and the penultimate has also a pair 

 of small postero-lateral teeth. 



The telson is about twice as long as the last somite, cylindrical at 

 the base, with the narrow post-anal part occupying about half of 

 its length. There appear to have been about nine pau*s of lateral 

 spinules. 



Fig. 67.— D I a s t ylis 



ASPERA, FEMALE, 

 CARAPACE FROM 

 ABOVE. 



