of the outer edge. Last pair of legs very similar in shape to those in M. 

 longicornis, the inner expansion being rather prominent. 



Body in the living animal whitish pellucid, and ornamented with irregular 

 patches of a light reddish brown or chestnut-coloured pigment. 



Length of adult female 4.50 mm. 



Male unknown. 



Remarks. -This is much the largest of the species observed by me, and 

 I therefore at first believed it to be the M. grandis of Giesbrecht. On a closer 

 examination I have, however, found it to differ in some respects very essenti- 

 ally from that species, being in reality much more nearly related to the 2 

 preceding species, though easily distinguishable from them by the rather 

 different shape of the body. 



Occurrence. A solitary female specimen of this form was taken, many 

 years ago, at Hval0r, outside the Christiania Fjord. 



5. Monstrilla leucopis, G. O. Sars, n. sp. 



(PI. VII) 



Specific Characters. Female. Body exceedingly slender and elongated, 

 resembling somewhat in shape that of M. longiremis. Cephalic segment 

 considerably exceeding half the length of the body, and of a narrow cylindrical 

 form. Tail comparatively short, scarcely attaining half the length of the ex- 

 posed part of the trunk; genital segment rather dilated at the base, and 

 without any trace of a dorsal suture; ovigerous spines of moderate length. 

 Caudal rami rather large, exceeding in length the last 2 segments combined, 

 and only slightly divergent, inner edge perfectly straight, outer considerably 

 protuberant in front of the middle; each ramus provided with 5 setae, 3 of 

 which issue from the narrowly rounded apex, the other 2 from the outer edge, 

 the latter of very unequal size, the proximal one being normally developed, 

 whereas the distal one is greatly reduced, and only slightly exceeds in length 

 the corresponding ramus. Eye inconspicuous, and replaced by an opaque 

 whitish substance apparently answering to the ocular pigment. Antenna rather 

 slender, though not nearly attaining the length of the cephalic segment, and 

 having their 5 joints more distinctly defined than in the preceding species, 

 none of the setae attached to the terminal joint ramified. Oral tubule rather 

 small, and occurring somewhat in front of the middle of the cephalic segment. 

 Natatory legs without any denticle inside the 2nd basal segment, outer ramus 

 rather produced and having the outer edge of the terminal joint perfectly 



