64 MB. E. J. MIEBS OS GBEENLAFO CRUSTACEA. 



CUMACEA. 

 DlASTYLIS RaTHKII. 

 Cuma Rathkii, Kroyer, Nat. Tidsskr. iii. p. 513, pis. v. & vi.figs. 17-30 



(1840-41), (N.R.) ii. pp. 144, 207, pi. i. tigs. 4 & 6 (1846-49); Voy. 



en Scand. Atlas, Crust, pi. v. figs. 1 a-u. 

 Diastylis Rathkii, G. O. Sars, Aberrante Krebsdyr. Cumacea, in Christ. 



Vidensk.-Selsk. Forhandl. p. 160 (1864); Svensk. Vetensk.-Akad. 



Handl. ii. (No. 6) p. 7, pi. iii. figs. 8, 9 (1873). 



A single individual was included among the species dredged off 

 Hare Island in about 30 fathoms. Its length is about 6| lines. 

 It is found on the Atlantic coast of Northern America and in the 

 seas of South Greenland, Scandinavia, and Britain, but more 

 abundantly in the higher latitudes, and is perhaps the most 

 common of the northern species of this curious group. 



Isopoda. 



Idotea, sp. yg ? 



There is in the collection a specimen, apparently referable to 

 this genus, which, on account of its very small size and imperfect 

 condition, cannot be made the type of a detailed specific descrip- 

 tion, yet seems to be quite distinct from all the species known to 

 me. The head is comparatively large, the frontal margin with a 

 Very slightly prominent broad median lobe. The eyes (black) are 

 placed' in the middle of the lateral margins of the head. The 

 sides of the body are parallel, the segments of equal width, the 

 three last segments having the postero-lateral angles subacute. 

 There are four perfectly distinct postabdominal segments, the 

 first three very short ; the terminal segment is triangulate in 

 form, with the angles rounded, broadest at base, where it exceeds 

 in breadth the preceding segments, and with the sides convergent 

 to the distal extremity, which is broad and obtusely rounded. 

 The antennules are apparently four-jointed ; the antennae have 

 six joints exposed, the four first thickened, and the two terminal 

 slenderer and more elongated; the terminal ends in a pencil of 

 fine hairs. The legs are imperfect, but are armed with subter- 

 minal as well as a terminal claw. The operculiform caudal ap- 

 pendages are not oblong, but rather oval in shape, narrowing to the 

 distal extremity. Length l-§ line. 



The only example collected was obtained by washing seaweed 

 taken on the surface of the North mid- Atlantic in lat. 57° 59' N. f 



