ON THE MARINE ZOOLOGY OF THE IRISH SEA, At9 
dredged and trawled :—between Port Erin and Calf Island ; depth 17 to 
22 fathoms. 
Two of these expeditions—those at Easter in the ‘ Rose Ann, and at 
the end of April in the ‘John Fell’—were particularly successful, and 
resulted in the capture of a number of new and interesting species. 
Amongst these is a large green Gephyrean worm, which is either Thalas- 
sema gigas, M. Miller, or a new species of Thalassema with a remarkable 
pigment ; and a Cumacean, for which a new genus is necessary. 
Additions have been made during the year to most of the groups of 
invertebrate animals, and these will be found noted in the lists below i 
but Mr. A. O. Walker has prepared the following special account of the 
higher Crustacea obtained on these expeditions: — 
The following species of Crustacea MALacostraca have been added ' 
to the fauna since the last report. Nearly all were dredged off the S. end 
of the Isle of Man in the ‘John Fell’ expedition, from April 22 to 24, 
1896. 
PopopHTHaLMA :—Portunus corrugatus (Pennant).—8.E. of Calf 
Sound, 26 fathoms. 
Nika edulis, Risso.—Co. Down Coast (Ascroft). From stomach of 
whiting, 12 m. S.W. of Chicken Rock, 33 fathoms. 
Scuizopopa :—Lrythrops serrata, G. O. Sars ; 12 m. S.W. of Chicken 
Rock, 33 fathoms. 
Siriella armata (M. Edw.). Port Erin harbour, April 1896. 
Cumacea :—Fam. Leuconide. 
Leuconopsis, n. gen. 
Female with a distinct two-jointed appendage to the fourth pair of 
feet, not furnished with natatory sete. Lower antenne short, with the 
third joint conical, with a minute one-jointed rudimentary flagellum, 
Rami of uropoda subequal. 
Male with the third pair of feet each provided on the second joint 
with a pair of curved blade-like processes. 
Remaining characters as in Leucon. 
Leuconopsis ensifer, n. sp. 
Female :—Carapace about as long as the free thoracic segments, dorsal 
crest of fourteen teeth beginning about the middle of the upper margin, and 
curving down to the base of the rostrum; a small tooth on the upper and 
near the posterior margin ; lower margin with the anterior half coarsely 
toothed, and forming with the anterior margin an acute angle, the upper 
portion of which is finely toothed. Rostrum about quarter the length of 
the carapace, obliquely truncate, almost horizontal ; lower margin with 
two or three teeth near the extremity and two or three near the base. 
Fourth pair of legs with an exopodite or imperfect natatory appendage, 
two-jointed, reaching nearly to the end of the first joint, which is 
almost as long as the remaining four. 
Telson triangular, as in Lewcon. 
Uropoda with peduncle and both rami subequal in length ; peduncle 
almost spineless, inner ramus with six unequal spines on the inner and 
two on the outer side of the first joint ; second joint with two very short 
and slender spines on the inside ; outer ramus obliquely truncate, with five 
plumose seté on the inner side and four at the end. Length 5} mm. 
Male :—Upper margin of carapace as long as the free segments ; lower 
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