of the Fishery Board for Scotland. 260 
anterior one. Rostrum small. The antennules are very short, and 
moderately setiferous—seven jointed. The first joint is considerably 
dilated ; the second, which is only about half the length of the first, is 
also somewhat dilated. The third joint is nearly as long as the first. 
The fourth joint—which is furnished with a moderately long asthetask— 
and the last are of equal lengths, and are each as long as the second. 
The fifth and sixth joints are somewhat smaller than the others (fig. 16, 
Pl. X.). These differences are more clearly shown by the formula 
annexed—— 
Numbers of the joints, 1 
Proportional lengths of the joints, 12° 
Ht tess 1 NDE EM 
CISION GUA MaG 
Antenne small, three-jointed ; secondary branches very small, one-jointed 
(fig. 18, Pl. X.). The mandibles are also small; the mandible palp isobsolete, 
being represented by a single small hair (fig. 19, Pl. X.). The maxille are 
very small, the biting part is moderately broad, and armed with a few com- 
paratively elongate teeth. Thepalp isa smallcylindrical process,arising from 
a moderately broad base, and furnished with a few hairs (fig. 20, Pl. X.). 
Posterior foot-jaws small. They somewhat resemble those of Cylindro- 
psyllus levis (fig. 21, Pl. X.). The inner branches of the first four pairs 
of thoracic feet are all two-jointed, and shorter than the three-jointed 
outer branches. The two joints that compose the inner branches are, in 
each of the four pairs, more or less subequal, but those of the first pair 
are rather stouter than the others. All the four pairs of feet are small 
(figs. 7 and 8, Pl. XI.). The fifth pair are minute. Each consists of a 
small semicircular appendage bearing three or four small sete (fig. 9, 
Pl. XI.). The caudal furce, which are small and cylindrical, are scarcely 
twice as long as broad ; but each carries a long terminal spiniform seta, 
and also a few small hairs (fig. 11, Pl. XI). 
The Male.—So far as can be made out, the male does not differ much 
from the female, except that the antennules are modified for grasping, as 
in other Harpactids. The fifth thoracic feet are also each provided with 
an elongate and stout spine,.in addition to the setz observed on the fifth 
pair of the female (fig. 10, Pl. X1.). 
Habitat.—Brackish water-pools on the shore near Hunterston, Firth 
of Clyde. Rather rare. 
Remarks.—This Copepod is somewhat like a Moraria or a Maraeno- 
biotus in general appearance, as well as in some of the structural details ; 
but it differs from these two genera, not only in the form of some of the 
mouth organs, and of the fifth pair of thoracic feet, but in other details of 
structure as well. Neither does it agree with Cylindropsyllus, although 
it has a general resemblance to the members of that genus. For these 
and other reasons, I have instituted for its reception the genus Lepto 
caris (Greek—leptos, slender ; karis, a shrimp). 
Idya cluthe, sp. vu. (Pl. XIL, figs. 2-6). 
Description of the Female.—Length of the specimen figured, 1°17mm. 
gy of aninch). Somewhat like Idya furcata in general appearance, but 
rather more slender (fig. 2). The antennules are moderately short ; being 
only about two-fifths of the length of the thorax, they resemble generally 
the antennules of Zdya furcata, but the entire length of the first four 
joints is proportionally shorter. The first four joints are sub-equal in 
length ; the fifth is rather shorter than the one next to it; while the 
seventh is distinctly smaller than either the fifth or sixth (fig. 3). The 
