i6 G. o. SARS. M.-N. Kl. 



cumbent corner slightly denticulated anteriorly, lower edge straight and 

 obliquely ascending, rostral projection extremely small, and occurring just 

 in front of the insertion of the antennulae. Carapace in male, seen later- 

 ally, narrower, gradually widening behind, terminal prominence less distinct 

 and not defined above by any sinus. Eye rather large, located within 

 the frontal part of the head; ocellus small, rhomboidal in form. Tail of 

 the usual structure, terminal claws without any denticles at the base. 

 Colour ochraceous, turning to pale chestnut along the back and lower 

 edge of the carapace. Length of adult female 2.40 mm., of male 0,80 mm. 

 Remarks. The present new species is nearly allied to the European 

 5. scrrulatits Koch, but differs in the somewhat different form of the head, 

 and in the circumstance that the hind edges of the valves, below the 

 posterior prominence, are quite smooth, not, as in that species, serrulate. 



Description of the female. 



The length of the largest specimens measures nearly 2^/2 mm., and 

 this form accordingly somewhat exceeds in size the European species, 

 S. serriilatiis. 



The general form of the body (see figs i & 2) is that characteristic 

 of the genus, being rather broad, almost navicular. 



Seen laterally (fig. i), the carapace exhibits a broad, somewhat rhom- 

 boidal form, with the dorsal margin obliquely curved, its greatest curva- 

 ture occurring behind the middle. The free edges of the valves are 

 bulging in front, and in the middle nearly straight and horizontal, wheras 

 behind they ascend obliquely towards the posterior prominence of the 

 carapace. The latter, which extends nearly in the longitudinal axis, is 

 distinctly projecting, though obtuse at the tip, and is defined above by 

 a well-marked sinus, the edge of which is minutely denticulate. The ad- 

 joining edges of the valves, on the other hand, are quite smooth through- 

 out. As in other species, inside the lower edges of the valves a some- 

 what llexuous ridge is traceable, fringed with delicate bristles, which partly 

 project beyond the valves at their anterior and posterior corners. Seen 

 from above or beneath (fig. 2), the carapace appears rather tumid, with 

 the greatest width in front of the middle, its posterior part narrowing 

 gradually and terminating in an obtuse point. 



The head is comparatively small, and, seen laterally (fig. i), of a 

 somewhat triangular form. It is defined above from the carapace by a 

 distinct, though small notch ; but its dorsal face is otherwise continuous 

 with that of the carapace, both forming together a perfectly even curve. 

 Anteriorly it terminates in a procumbent frontal part, which forms an 



