developed setae, 2 apical and 2 lateral. Eye very fully developed, especially 

 in male. Antennae in female 4-articulate, in male much larger and distinctly 

 5-articulate, with the usual hinge between the last 2 joints. Oral tubule 

 occurring far in front. Natatory legs built in the usual manner. Last pair of 

 legs, however, in female of rather a peculiar structure, being somewhat fusi- 

 form in shape, and each produced into 2 smooth conical lappets, the outer 

 of which is the more prominent; setae of these legs not, as usual, attached to 

 the terminal edge of the leg, but arranged in a line crossing the base of the 

 outer lappet. Male without any trace of these legs, but having the copulative 

 appendage normally developed. 



Remarks. This new genus is established to include the anomalous form 

 recorded by Scott under the name of Monstrilla dubia. Indeed, I have found 

 it impossible to place this species either in the genus Monstrilla or in that of 

 Cymbasoma, as it in some respects seems to combine characters of both these 

 genera, in other respects to differ conspicuously from either of them. 



12. Monstrillopsis dubia, (Scott). 



PI. XIV. 



Monstrilla dubia, T. Scott, Twenty-second Ann. Rap. of the Fishery Board for Scotland, Part III, 

 p. 247, PI. XIII, fig. 14, PI. XIV, figs. 1618 



Specific Characters. Female. Body exceedingly slender and narrow, 

 with the anterior division not at all dilated. Cephalic segment exceeding the 

 remaining part of the body by Vs of its length, and narrow cylindrical in 

 form, being almost of equal width throughout. Tail about equalling half the 

 length of the exposed part of the trunk; genital segment a little longer than 

 the other 2 segments combined and slightly dilated at the base, with the 

 ventral face somewhat protuberant; ovigerous spines of moderate length; anal 

 segment somewhat flattened and sharply defined from the rather small middle 

 segment. Caudal rami rather produced, exceeding somewhat in length the 2 

 preceding segments combined, and slightly divergent, each ramus provided 

 with 4 setae, one about in the middle of the outer edge, 2 at the apex, and 

 one inside at some distance from the end. Eye very conspicuous in the 

 living animal, with dark pigment and all 3 lenses well developed. Antennae 

 exceeding somewhat in length Vs of the cephalic segment, and composed of 

 4 well defined joints, the last of which is fully as long as the other 3 com- 

 bined; none of the setae ramified. Oral tubule well marked, and occurring 

 near the frontal part of the head. Natatory legs with the outer ramus con- 



