13 



taken by the aid of the tow-net .near the surface of the sea. The movements 

 of the animal are very rapid, and are performed in abrupt bounds, whereby 

 the body is kept in a more or less erect position. Male specimens seem to 

 occur in nearly same number as the females. 



Distribution. British Isles (Thompson, Scott), Skagerak (Aurivillius). 



3. Monsirilla longiremis, Giesbrecht. 



(PI. IV & V) 



Monstrilla longiremis, Giesbrecht, Pelagische Copepoden des Golfes von Neapel, p. 589, PI. 



46, figs. 10, 14, 22, 37, 41. 



Specific Characters. Female. Body considerably more slender than in 

 the preceding species, with thinner and scarcely at all granular integuments. 

 Cephalic segment occupying rather more than half the length of the body, 

 and slightly narrowed in its anterior part, with no distinct dilatation in the 

 middle. Tail agreeing with that in M. longicornis, as regards its relativ size 

 and its segmentation, but having the ovigerous spines considerably more 

 elongate. Caudal rami comparatively narrower than in that species and 

 remarkably divergent; number of marginal setae, as in M. longicornis, 5 on 

 each ramus, the innermost but one conspicuously shorter than the others. Eye 

 inconspicuous. Antennae exceedingly slender and elongated, considerably ex- 

 ceeding in length the cephalic segment, and, as in the preceding species, 

 having all the joints, except the 1st, confluent. Oral tubule rather small, and 

 occurring about in the middle of the cephalic segment. Natatory legs resemb- 

 ling in structure those in M. longicornis, but differing in the presence of only 

 a single denticle inside the 2nd basal segment, and in the total absence of 

 any crenulations on the outer edge of the terminal joint of the outer ramus. 

 Last pair of legs comparatively narrower, with the inner expansion less pro- 

 minent and evenly rounded off; number of marginal setae as in M. longicornis. 

 Ova attached to the genital spines very mnnerous, and in some cases accu- 

 mulated to form an oblong oval mass extending far beyond the limits of the body. 

 Male of rather small size, as compared with the female, but exhibiting 

 a much similar slender and narrow form of the body. Cephalic segment 

 nearly perfectly cylindrical in shape and exceeding somewhat in length the 

 remaining part of the body. Tail, as in the male of M. longicornis, distinctly 

 4-articulate, with the copulative appendage of a very similar structure. Caudal 

 rami agreeing in shape with those in female and spread out in the same remark- 

 able manner, each of them, however, only provided with 4 setae. Antennae 

 much more slender than in the male of M. longicornis, with the 2nd joint of 



