16 G. o. sars. [No. 7. 



Specif c Characters. — g. Carapace, as seen laterally, very 

 oblique, subrhomboidal, dorsal edge forming posteriorly a very 

 sharp curve and terminating in a short and broadly obtuse pro- 

 minence somewhat above the longitudinal axis; ventral edges of 

 valves bulging out a good deal anteriorly and joining with a 

 uniform curve the very oblique posterior edges. Head compara- 

 tively small, front subangular, inferior edge well-nigh straight 

 and defined from the short recurved rostrum by an angular notch. 

 Shell obliquely striated, posterior part of dorsal edge strongly 

 denticulate. Eye of usual appearance. Ocellus very small, punc- 

 tiform. Tail rather broad, supraanal angle obtuse, caudal claws 

 elongate, very slightly curved, armed at the base with a regular 

 series of about 12 strong secondary teeth; anal denticles 9 on 

 either side, rapidly increasing in size distally. Colour light 

 ochraceous, valves with irregular patches of golden yellow. Length 

 of adult female reaching nearly 2 mm. 



Bemarhs. — There can, I think, be but little doubt as to 

 the identity of the present form with that described - though 

 very insufficiently — by Dana under the above name. The ap- 

 parent dissimilarity as to the form of the carapace and the 

 structure of the antennae and tail must. I feel sure, be ascribed 

 to a less careful examination, or maybe to some inaccuracy on 

 the part of the lithographer. The species is very nearly related 

 to the Northern form, 8. exspinosus (Degeer) (= S. congener 

 Koch), but on closer comparison it may be readily distinguished 

 by the peculiar oblique form of the carapace and the well-marked, 

 though obtuse, projection of its posterior extremity; likewise too 

 by the broad tail, and more especially by the highly character- 

 istic armature of the caudal claws. 



Description. — The length of the largest specimen observed 

 is not fully 2 mm., and hence does not quite attain the size of 

 the European species 8. exspinoms. 



Viewed laterally (PI. 2, fig. 1), the carapace exhibits a vei) 

 oblique, almost rhomboidal form, the length somewhat greater 

 . than the height. The dorsal edge, throughout the greater part of 

 its length, is but very slightly arched; posteriorly, however, it 



