228 COPEPODA 



somite. The Li 2 of the maxillulae has 2 not 3 setae. The Ri 2 of the fourth foot has no "corona of 

 spines", but a number of fairly long bristles, and the fifth feet seem to be somewhat different. 



73. Onchocalanus cristatus Wolf. 

 (PI. VII figs 6 a e; PI. VIII figs 17 a f). 



1904. Xanthocalanus cristatus 11. sp. Wolfenden, p. 119, pi. 1908. Onchocalanus cristatus Wolf. Farran, p. 49. 



IX figs 18 19. 1908. Xanthocalanus cristatus Wolf. Wolfenden, p. 34. 



1905. Onchocalanus trigoniceps n. sp. G. O. Sars, p. 20. 1908. v. Bremen, p. 62 fig. 70 



1906. Xanthocalanus cristatus Wolf. Pearson, p. 20. 1909? Onchocalanus cristatus Wolf. A. Scott, pp. 82 83, pi. 

 1906? similis n. sp. Esterly, pp. 68 69^159 13. ; XXXIV figs I 8. 



1907. Onchocalanus cristatus Wolf. G. O. Sars, p. 3. I 1911. Wolfenden, pp. 277278. 



Description. f$. Size of female from Thor St. 183 was 8-15 mm.; anterior division 6-45 mm.; 

 urosome 170. Another specimen measured 7-5 mm. Wolfenden's specimen measured 5-5 mm., Sars's 

 7 mm. and Scott's 6-6 mm. 



The shape of the body is like that of O. magnus, but it is more slender; the first as well as 

 the fifth thoracic somite is well marked out in front. The head (PI. VIII fig. 17 a) is well raised, and 

 surmounted with a dorsal low crest, visible in dorsal as well as in lateral view. The rostrum consists 

 of a basal portion and two fairly long somewhat divergent spines without distinct terminal filament. 

 The lateral corners are triangularly produced and terminated with a distinct tooth. 



The abdomen is a little more than one fourth as long as the anterior division; the genital' 

 somite is like that of O. magnus, but is less produced below. The comparative length of the abdominal 

 somites and the furcal branches is 28, 18, 13 and 6; the somites are hairy in a similar way as in 

 the other species. 



The antennulae are like those of O. magnus, and extend about to the end of the furca; the 

 only difference is found in the slightly different measurements of the segment 13, which is 1^24 (not 

 i - 4) as long as segment 12, and of segment 24 which is i - i as long as segment 23 (not a little shorter). 

 The antennae, mandibulae and maxillulae are scarcely different from those of O. magnus. The maxillae 

 are like those of the preceding species ; the endopodite possesses in addition to a short seta of usual 

 structure a long slender sensory seta and 5 fairly long ones, the slightly enlarged part of which is 

 more or less "brush-shaped". The maxillipeds are like those of the preceding species, but the third 

 outer segment has 4 instead of 3 strong curved spines. The first pair of legs differs only by rather 

 unimportant details in the armature of the posterior surface. The Se of the first inner segment is 

 long, slender, and distinctly pointed in the second pair of legs. The third as well as the fourth pair 

 of legs differs from O. magnus in the details of the arrangement of the hairs, and by the curiously 

 contorted terminal spine. The fifth pair of legs consists of three segments, of which the third, attenuated 

 one, is longer than the second, but shorter than the two basal ones combined; it has, as seen in fig. 

 6 a PL VII, a terminal and two outer spines. The anterior surface is smooth, while the sides as well 

 as the posterior surface are all over covered with fairly strong setae or spines. 



The labrum (PL VIII fig. 17 a) etc. are not in any features of great interest different from the 

 corresponding organs of the preceding species. 



