of the Fishery Board for Scotland. 244 



The antennules of the male, which are proportionally rather longer than 

 those of the female, are five-jointed, the last joint being hinged to the 

 preceding one (fig. 1, pi. xv.). 



The first and second segments of the male abdomen are not coalescent 

 as in the female, but otherwise the two sexes are nearly alike. 



The armature of the furcal joints (fig. 2, pi. xv.) is similar to that of 

 the female. 



The fifth pair of feet resemble very closely the fifth pair of the male of 

 M. longiremis. 



Habitat— Read of Loch Fyne (Firth of Clyde), November 28, 1899, 

 one female, and January 30, 1901, a male and a female. 



Professor G. S. Brady records a Monstrilla, obtained at Cullercoats 

 in July, 1900, which he thinks may be the male of M. grandis, 

 Giesbrecht,* and I. C. Thompson mentions the occurrence of the same 

 species in the vicinity of the Channel Islands.t 



Monstrilla longicornis, I. C. Thompson. PI. xiii., fig. 1-7. 



1890. Monstrilla longicornis, I. C. Thompson, Trans. L'pool. Biol. 



Soc, vol. iv., p. 119, pi. iv., figs. 1, 2, and 4 (s). 

 1892. Monstrilla longiremis, Giesb., Pelagischen Copepoden des 



Golfes von Keapel, p. 589, pi. 46, figs. 10, 14, 22, 37, and 



41 (<j>). 

 1902. Monstrilla longiremis, T. Scott, 20th Eept. Fishery Board 



for Scotland, pt. iii., p. 469, pi. xxv., figs. 3 and 4 ($). 



The antennules in both the female and male are elongated and slender, 

 being in some examples nearly half as long as the cephalothorax and 

 abdomen combined ; but their length seems to vary to some extent in 

 different individuals, and those of the male appear to be proportionally 

 rather longer than in the female. The male antennules are composed of 

 six joints, and the articulation between the fifth and sixth is so hinged 

 that the sixth joint can be folded inwards ; the second and last joints are 

 of nearly equal length and considerably longer than any of the others 

 (fig. 6). In the female antennules all the joints except the first appear 

 to be coalescent, so that each antennule is apparently only two-jointed 

 (fig. 3). 



The fifth thoracic feet of the female consist each of a sub-cylindrical 

 plate, but the proximal half of the leg is rather wider than the lower half 

 and is defined from it by a distinct notch on the inner margin, and from 

 this notch there springs a moderately long seta ; three other setse spring 

 from the distal extremity of the leg, but the innermost one is short while 

 the other two are elongated; all the setae appear to be more or less plumose 



(%• *)■ 



The fifth feet of the male are somewhat rudimentary, each being 

 represented by a single moderately long plumose seta which springs from 

 a small tubercle near the lower ventral margin of the last thoracic seg- 

 ment. The genital appendages are narrow and spiniform (fig. 7). 



The furcal joints in the female are each furnished with five moderately 

 long seta3, but there are only four setse to each of the furcal joints in the 

 male. This appears to be the only British species of Monstrilla in which 

 the number of furcal setae in the female is five. 



The male of Monstrilla longicornis does not appear to have been 

 previously recorded except by I. C. Thompson. 



* Nat. Hist. Trans. Norihumo., Durham, and Newcastle, vol. xiv., p. 64, pi. iv., fig. 1-3. 

 fJourn. Marine Zool. and Microscopy, vol. ii., p. 97 (No. 8, December, 1897). 



