COPEPODA 



231 



It differs from Scott's species from the Malay Archipelago by the less slender fifth foot 

 without inner spine, and by the endopodite of the maxillae, which does not possess 6 strongly brush- 

 shaped setae. 



This species is nearly related to Ester ly's X. similis; it differs, according to him, especially by 

 the four segments of the fifth pair of legs (PI. XIII fig. 77). As the only examined female (from the 

 Gulf of California), which is 6-5 mm. long, is a young one of the penultimate stage, I think, although 

 the fifth pair of legs is completely like the four-segmented one which I have examined of the same 

 stage (PI. VIII fig. 17 f), that a more detailed description is needed of specimens from this region before 

 settling the question. 



74. Onchocalanus hirtipes G. O. Sars. 

 (Text-figs 74 a i). 



1905. Onchocalanus hirtipes n. sp. G. O. Sars, p. 20. 

 1908. G. O. Sars. Farran, p. 49. 



1909. Onchocalanus hirtipes G. O. Sars. A. Scott, p. 83, pi. 



XXXIV figs 917. 



Description, fo. Size of female from Thor St. 183 was 5-3 mm.; anterior division 4-0 mm.; uro- 

 some 1-3 mm. Sars' specimens measured 47mm., Farran's 57 and Scott's 5111111. 



The body is moderately slender. The head is suddenly, but not very much, raised, and does 

 not possess any crista. The fairly long rostrum has two only slightly divergent spines, each possessing 

 a long, slender terminal filament. The first as well as the fifth thoracic tergites are well marked in 

 front; the lateral corners are somewhat triangularly produced, but rounded (text-fig. 74 a). 



The abdomen is one third as long as the anterior division; the genital somite is strongly pro- 

 duced below, and has a short receptaculum; in dorsal view it is seen to be much broader somewhat 

 in front of the middle; in front and in a less degree behind it becomes suddenly narrow. The serrated 

 seam along the hinder margin from the second to fourth somite is well developed. Short, stiff, scattered 

 hairs are found on each side of the genital somite, and tufts of fairly long hairs on the ventral surface 

 of the fifth somite. 



The antennulae reach about to the end of the genital somite; the appendages are scarcely 

 different from those of C. chelifer, except the Sp. of the segment 24, which is one third removed from the 

 tip of the segment, and extends to the end of segment 25. The segment 13 is i'6 as long as segment 

 12, and the segment 24 is a little longer than 23. 



The exopodite and the endopodite of the antennae are of almost equal length; the Si of the 

 first basipodite is as in the preceding species short. The mandibulae and maxillulae are like those of 

 C. chclifer, but for the presence of n setae in the endopodite (5 in the Ri III) of the maxillulae. The 

 structure of the maxillae is like that of the two preceding species; the endopodite has, in addition to 

 a single vermiform seta, 7 rather curiously developed "brush-shaped" setae, similar to those figured in 

 Scott's fig. 14 (PI. XXXIV). The maxillipcds are similar to those of the preceding species; the com- 

 parative length of its main divisions is 65, 80 and 47; the sensory setae of the second basipodite is 

 distinctly brush-shaped, and scarcely twice as long as wide on the left side, but on the right side it 

 is like that of other species; the number of curved setae in the endopodite is as in the preceding 

 species, but they are comparatively weaker. 



