81 



at the end, and provided with 6 marginal setae, 3 very small on the outer 

 edge, and 3 on the tip; inner expansion of proximal joint more distinctly 

 defined than in the type species, and carrying 3 well-developed marginal setae. 

 Ovisac very small. 



Colour whitish grey. 



Length of adult female 0.87 mm. 



Remarks. The present form, first described by I. C. Thompson, may 

 at once be distinguished from the type species, M. irrasus Scott, by the 

 peculiar horn-like process springing off from the dorsal face of the cephalic 

 segment. In the more general structural details it shows a near relationship 

 to that species, though, on a closer comparison, some well-marked minor 

 differences may be found to exist, especially as regards the mutual relations 

 of the joints in the anterior antennae and the shape of the last pair of legs. 



Occurrence. I have only met with this form in a single locality on 

 the Norwegian coast, viz., at Riser, where it occurred occasionally in a depth 

 of about 50 fathoms, coarse muddy sand. All the specimens obtained were 

 of the female sex. 



Distribution. Liverpool Bay (Thompson). 



66. Mesocletodes abyssicola, (Scott). 



(PI. LV). 



Cletodes abyssicola, Scott, On some Entomostraca collected in the Arctic Seas by W. Bruce. 

 Ann. Mag. Nat. Hist. ser. 7, Vol. VIII, p. 347, PI. V, figs. 18. 



Specific Characters. Female. Body comparatively a little less slender 

 than in the preceding species, with the segments coarsely denticulate at the 

 hind edge. Cephalic segment somewhat tumid, with the frontal part broadly 

 rounded off; rostral projection very small, almost obsolete; dorsal face of the 

 segment considerably vaulted and armed behind, as in the preceding species, 

 with a strong spiniform process still more prominent and curved than in that 

 species. Urosome, as in the other species of the present genus, nearly of 

 uniform width throughout, with the last segment rather large; anal opercle 

 tipped with a strong upturned tooth. Caudal rami very narrow and quite 

 excessively produced, occupying more than Vs of the entire length of the body, 

 each ramus provided in the middle with 2 small bristles, the one lateral, the 

 other dorsal; apical setae very short. Anterior antennae comparatively slender, 

 exceeding somewhat in length the cephalic segment, and, as in the preceding 

 species, composed of 7 joints, the 2nd of which is rather broad, though 



12 Crustacea. 



