COPEPODA 227 



comparatively shorter in the two outer segments. Anteriorly, hairs are only found in the second basi- 

 podite, where, f. inst, laterally a large group of long setae is found. 



The fifth pair of legs (fig. 5 d) consists of three segments ; the exopodite has a terminal and two 

 outer spines ; the anterior surface is almost smooth, while the posterior surface as well as the sides 

 are covered with long setae. 



In front of the rather prominent labrum proper a prominent cpistoma (PI. VII fig. 5 a), which is 

 densely covered with long bristles (fig. 5e), is found; the bristles of the labrum are neatly arranged into two 

 anterior groups of long bristles, about three lateral groups of shorter hairs and a single marginal row. 

 The oral surface of the labrum (fig. 5 f) is anteriorly densely covered with a number of short minute 

 prickles; scarcely distinguished from these, two lateral groups of hairs are found, probably corresponding 

 to two groups in C. chelifer. Almost in the middle, on each side, about three almost completely fused 

 groups of short bristles as seen in figure are found, and more behind, an oblique group of delicate 

 hairs is found. In the middle densely placed granules are found in transverse areas. No distinct 

 lamina labialis is found; in front of the serrula 6-dentata (fig. 5 g) a large inner group of short granules 

 is found, and an outer longitudinal row of fairly long hairs. Behind, a horse-shoe shaped group of 

 granules is found on each side and, well separated from this, as seen in fig. 5 e, irregularly placed short 

 hairs. Along the inner margin of the labial lobes inwards short spines, and more outwards long bristles, 

 are found. 



Y£ (St. V). Size of female from Thor St. 183 was 6-25 mm.; anterior division 5 mm.; urosome 

 1-25 mm. 



The shape of the body is scarcely different from that of the adult, but for the regularly pointed 

 lateral corner. The comparative length of the four abdominal somites and the furcal branches is 10, 

 15, 13, 8 and 6. The abdominal somites are almost completely smooth. But for the comparatively 

 shorter fifth foot, the appendages are scarcely different from those of the adult females. 



Occurrence. The Thor has taken this species at two stations. 



ir / 7 1904 St. 183 6i°30 h. N. i7°o8 L. W. Yt. 1800 M. Wire 2 f ?, 2 y$ (V). 

 % 1905 St. 72 57°52 L. N. 9 °35 U W. Yt. 1500 M. Wire 1 y? (V). 



Distribution. This species has previously been found in the Antarctic Seas. 



Wolfenden has originally given the name X.magnus to a species about 8 - 8 mm. long with 

 pointed lateral corners. Later on he has subdivided his original species into a smaller one with rounded 

 lateral corners to which he applies the name O. magnus, and a larger one which he names O.frigidus. 

 I think the name magnus must necessarily be used for the bigger species. 



I am very doubtful, if my North Atlantic species is really identical with the Antarctic one; Wolf- 

 en den's description, however, is in several important points too incomplete to settle the question. 



The differences are the following. In my specimens the first as well as the fifth thoracic 



somites are well marked in front; the genital somite is not as long as the following three somites, 



the vulva has no "lateral flap" on each side, and the genital somite can scarcely be called "very swollen 



ventrally". The antennulae are longer, as they reach distinctly beyond the middle of the genital 



29* 



