24 G- (^- ^ARS. M.-N. Kl. 



The surface of the shell is nearly quite smooth, without any trace 

 of a longitudinal striation. Only near the free edges of the valves a very 

 faint and indistinct reticulation is sometimes traced. The inferior edges 

 of the valves are finely ciliated, the cilia being more prominent in the 

 middle. If the animal is viewed from the ventral side (fig. 6), these edges 

 are found to be excised in front of the middle, so as to leave between them 

 an oblong oval, open s]:)ace, through which the spines and setae of the 

 anterior pairs of legs may be exserted. 



The eye is of moderate size, with the crystalline bodies well marked, 

 though not very large. 



The ocellus is somewhat smaller than the eye, and located about 

 half way between the latter and the tip of the rostrum. 



The antennulæ are of the usual narrow subfusiform shape, and do 

 not extend to the tip of the rostrum. 



The antennae are of moderate size, and quite normally constructed. 



The lamellar expansion of the labrum is rather large and securiform 

 in shape, with the edge perfectly smooth. 



The tail (fig. 7) is very slender and considerably narrowed distallj^ 

 exhibiting at some distance from the base, just above the anal sinus, a 

 A^ery slight angle. The tip is deeply incised, the incision being defined 

 in front by an obtuse projection carrying the terminal claws. The latter 

 are rather strong, horn-coloured, and nearly straight, carrying each, at the 

 base, a remarkably large secondary denticle. The posterior edge is armed, 

 below the anal sinus, with a double row of small, but well defined den- 

 ticles, about 12 in each row, the outer ones being more crowded. The 

 caudal setæ are rather small. 



The alimentary tube forms an almost double wind, and has, at the 

 junction with the rectum anteriorh', a rather elongate cœcal appendage. 



The matrix generally contains but A single ovum, or eml)ryo, more 

 rarely 2, arranged the one in front of the other. Of winter-eggs there 

 is, invariably, but a single one placed in the anterior part of the matrix 

 (see figs 5), and, in individuals carrying such an ovum, the dorsal part of 

 the carapace often assumes a rather tiark hue. 



The adult male (fig. 8) scarcely exceeds in length 0,70 mm., and 

 does not differ much in general apparance from young females. On a 

 closer examination, it is, however, easily distinguished by the usual sexual 

 characters. Thus the antennulæ are comparatively thicker than in the female, 

 with the olfactory papilJæ more fully developed. Idie ist pair of legs 

 are each provided with the usual, antericily curving hook, which however 

 is comparatively less strong than in the male of Leydigia, and scarcely 



