REPORT ON THE CUM ACE A. 63 



Besides the typical species, Nannastacus unguiculatus, Spence Bate, another very- 

 distinct species, Nannastacus longirostris, has been described by the author from the 

 Mediterranean, and a third species from the Challenger Expedition is now added. 



13. Nannastacus suhmii, n. sp. (PI. X. figs. 4—5). 



Specific Characters. — Form of body rather stout, especially in female. Carapace 

 very large, more than twice as long as the exposed part of trunk; dorsal surface evenly 

 vaulted, without any spines or projections; posterior part somewhat gibbous; antero- 

 lateral corners greatly produced, but terminating in a blunt point; pseudorostral 

 projection in female tubular and obliquely ascending, in male very short and rounded. 

 Eyes with three well-defined corneal facets, much larger in male than in female. Legs 

 nearly as in Nannastacus unguiculatus. Uropoda with the scape very short, inner 

 branch elongate, outer exceedingly minute. Length scarcely exceeding 2 mm. 



Remarks. — This form is very nearly related to the typical species, Nannastacus 

 unguiculatus, Spence Bate, but may readily be distinguished by the female wanting 

 every trace of the peculiar laminar spines adorning the carapace, as well as the epimeral 

 plates of the exposed segments of the trunk in that species. Moreover, the antero- 

 lateral corners are not sharply pointed but blunt at the tip, and these corners in the 

 male are comparatively more produced than in the male of Nannastacus unguiculatus. 



Description. — All the specimens of this form contained in the collection, having 

 been mounted together in Canada balsam on a glass-slide, a closer examination of 

 the anatomical details could of course not be instituted. Among tbe specimens 

 there is but a single female, the rest being males. The length of the body does not 

 exceed 2 mm. 



The form of the body (see PL X. figs. 4, 5) is rather short and stout, though a little 

 more slender in the male (fig. 5) than in the female (fig. 4), with the anterior division 

 somewhat longer than the posterior and rather ddated, especially in the female. 



The carapace is somewhat differently shaped in the two sexes. In the female 

 (fig. 4) it is very large and tumid, with the dorsal surface boldly arched and distinctly 

 gibbous in the posterior part. The pseudorostral projection is rather prominent, 

 forming a narrow tubular process, which ascends obliquely in front and is tipped with 

 small bristles. The antero -lateral corners of the carapace are greatly produced in the 

 form of conical processes, terminating in a blunt point. Between these processes and 

 the pseudorostral projection there is a broad shallow emargination, from the bottom of 

 which the antennulse are seen projecting. The inferior edges of the carapace form 

 together with the posterior an uninterrupted oblique curve, and are finely denticulate 

 in the anterior part. In the male (fig. 5 ) the carapace is comparatively much shallower, 

 with the dorsal line almost horizontal, and the pseudorostral projection far less 



