261 Part [1I.—Seventeenth Annual Report 
proportional lengths of all the joints are nearly as in the annexed 
formula— 
Number of the joints, 1:2: 3: 4:°5°6°7°8. 
Proportional length of the joints, 22 -°28:*25°24°6°9-:4:°18 
The antenne and mouth organs are similar to those of Jdya furcata. 
The first pair of thoracic feet resemble those of Jdya furcata, but the seta 
that springs from the end of the first joint of the outer branches is short 
and straight, and none of the terminal or sub-terminal sete bear secondary 
spine-like apical cilia so characteristic of Zdya jfurcata and one or two 
other members of the genus. The second joint of the inner branches is 
proportionally stouter than the same joint in ZJdya furcata, and the 
terminal claws are long and slender instead of being short and moderately 
stout. Moreover, the spines on the inner and outer aspects of the second 
basal joint are also small and slender (fig. 4). The second, third, and 
fourth pairs of swimming feet are rather more slender than the same 
appendages in Jdya furcata (fig. 5). The fifth pair of feet have the 
second joint long and slender, and the margins do not appear to be 
ciliated; the seta which springs from the inner angle, and also that 
which springs from the outer angle, of the basal joint are long and slender, 
while the terminal sete of the secondary joint are also elongate (fig. 6). 
The abdomen is elongate, being equal to nearly two-thirds of the length 
of the thorax; the first and second segments appear to be, at least partly, 
coalescent ; their combined length is equal to half the entire length of the 
abdomen ; the last abdominal segment is very small. The caudal furea 
are short, and about as long as broad. 
Habitat.—l.och Fyne and Firth of Clyde. Generally distributed, and 
apparently not very rare. 
Remarks.—This distinct species of Jdya appears to be unlike any 
previously described member of this genus. The two most prominent 
characters by which it may be distinguished from all closely allied species 
are—(1) The armature of the first pair of thoracie feet, and especially the 
long terminal spines of the inner branches, and (2) the long slender fifth 
feet. Jdya cluthe may by these two characters be distinguished at a 
glance even without dissection. Like other forms of Jdya, this one bears 
a comparatively large ovisac. Both males and females have been 
obtained, and both are equally distinct. Hitherto this species has 
occurred only in moderately deep water. 
Monstrilla dane (?), Claparede. 
Several specimens of Monstrilla, all of which appear to belong to the 
same species—viz., Monstrilla dane, Claparéde—have been obtained 
during the past year. They are all from the Clyde district, chiefly Upper 
Loch Fyne and Kilbrennan Sound. Usually one or two, rarely three or 
four, specimens were obtained in a single gathering. 
The gatherings in which Monstrilla was observed were from the follow- 
ing stations :—Station II. (three specimens), Station III. (one specimen), 
Station IV. (two specimens), Station VI. (three specimens), Station 
XIII. (two specimens), Station XIV. (four specimens), Station XVIL., 
two gatherings (one specimen each). These gatherings were all collected 
in August and November 1898, 
