1898— 1902. No. 18.] CRUSTACEA. 93 
Occurrence. — Several specimens of this form were found in 
the bottom-residue of 4 different bottles. In one of them, containing 
specimens taken on July 30, 1900, it occurred rather plentifully. 
93. Idyanthe! dilatata, G. O. Sars. 
One or two specimens of this peculiar form occurred in a bottle 
of specimens taken on July 12, 1900, in the bay at Land’s End. 
Fam. Thalestridez. 
94. Thalestris gibba (Kroyer). 
This form occurred occasionally in a bottle of specimens taken 
on July 17, 1902, east of the great glacier, North Devon, from a depth 
of about 3 fathoms. 
95. Phyllothalestris frigida (Scott). 
(Pl. 1V). 
Thalestris frigida, Tu. Scotr, Marine and fresh water Crustacea from 
Franz Josef Land. Linn. Soc. Journ. Zoology. Vol. XXVIII, p. 108, Pl. 7, 
figs. 1728, Pl. 8, figs. 1, 2. 
Specific Characters. — Female. Body comparatively strongly 
built, with the integuments highly chitinized. Cephalic segment large 
and deep, somewhat narrowed in its anterior part, and produced in 
front to a strong falciform deflexed rostrum terminating in a very acute 
point. Epimeral parts of the 3 succeeding segments less deep than in 
the type species, but terminating behind in a sharp angle. Last pedige- 
rous segment short, but rather broad, with the lateral parts somewhat 
produced. Urosome not much narrower than the anterior division and 
somewhat exceeding half its length, genital segment broader than it is 
long, and somewhat depressed, exhibiting on each side, like the 2 
succeeding segments, an obliquely transverse row of small denticles. 
Last segment well developed, though a little shorter than the preceding 
one. Caudal rami short, being scarcely longer than they are broad, 
and somewhat obliquely truncated at the tip, middle apical sete rather 
slender, the inner one being, as usual, the longer. Anterior antenne 
1 The name Idyopsis having been previously given by Prof. A. Acassiz to a 
genus of Acalephz, I propose the above change of the generic name. 
