19 



8. Monstrilla serricornis, G. O. Sars, n. sp. 



(PI. X, fig. 1). 



Specific Characters. Male. Body comparatively short and stout, and, 

 seen laterally exhibiting a somewhat clavate shape. Cephalic segment shorter 

 than usual, only slightly exceeding in length the exposed part of the trunk 

 and, seen dorsally, nearly of equal width throughout, its ventral face forming 

 anteriorly a rather prominent gibbous convexity, but without any distinctly marked 

 oral tubule. Tail rather narrow, and composed of 4 well defined segments, 

 the 1st of which is produced below to a sub-clavate copulative appendage 

 provided at the end on each side with a short auriculiform lobe. Caudal 

 rami comparatively small and somewhat divergent, each having the form of 

 a rounded oval lamella edged with 5 subequal setae. Eye inconspicuous. An- 

 tennas about equalling in length 2 /s of the cephalic segment, and rather strongly 

 built, being composed of 5 well defined joints, the last of which is, as usual, 

 very movably articulated to the preceding one, and somewhat knife-shaped, 

 with the inner sharpened edge divived at the extremity into 5 small recurved 

 denticles. Natatory legs of the usual structure. 5th pair of legs wholly absent. 



Colour not yet ascertained. Length of the body 1.75 mm. 



Female unknown 



Remarks. It is only provisionally that I refer the above-described re- 

 markable form to the genus Monstrilla, from which it in some respects seems 

 to differ rather conspicuously. As, however, only the one sex as yet has been 

 observed, its true relationship cannot at present be fully made out. The pecu- 

 liar armature of the antennae may suffice to distinguish at once this form from 

 any of the hitherto known Monstrillidae. 



Occurrence. Two specimens only of the present form have as yet come 

 under my notice, both of the male sex and exactly agreeing with each other. 

 The one was taken at Bukken, outside the Stavanger Fjord, the other at Kval0, 

 on the Nordland coast. 



Gen. 3. Cymbasoma, Thompson, 1888. 



Syn : Thamaleus, Giesbrecht (not Kroyer). 

 , Hcemocera, Malaquin. 



Generic Characters. General form of the body resembling that in Mon- 

 strilla. Tail however having the number of segments reduced in both sexes, 

 only 2 segments being present in female and 3 in male. Caudal rami com- 



