208 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Vessel : 



Remarks: The asymmetrical posterior thor- 

 acic margins, the right one of which extends 

 beyond the genital segment (fig. 1), serve to 

 identify the female of this species. The male 

 is recognized by the structure of the fifth feet 

 (fig. 5). 



Scolecithricella ctenopus (Giesbrecht, 1888) 



(Plate 16, figs. 6-15) 



Synonymy : 



Scolecithrix ctenopus Giesbrecht, 1888, Atti Ace. 

 Lincei Rend., ser. 4, 4 sem. 2: 338. 



Scolecithricella ctenopus Sewell, 1929, Mem. Ind. 

 Mus., 10: 212. 



Scolecithrix longicornis T. Scott, 1894, Trans. Linn. 

 Soc, Zool., 6: 50. 



Scolecithricella spinipedata Mori, 1937, The pelagic 

 Copepoda from the neighbouring waters of Japan, p. 

 53. 



Pacific records: Scott, 1909; Farran, 1936; Tanaka, 

 1953. 



Vessel : Station Occurrence 



Hugh M. Smith __ 94 1 juvenile female, 



1.28 mm. 



Do 178 2 females, 1.49, 1.53; 



1 male, 1.54 mm. 



Stranger 34 1 female, 1.46; 1 



male, 1.46 mm. 

 Orsom 10 1 female, 1.48 mm. 



Remarks: Farran (1936) found two females 

 which differed in size, segmentation of thorax 

 and structure of fifth feet. He also reviewed 

 the records and descriptions of S. longicornis 

 (Scott, 1894) and considered it a synonym of 

 S. ctenopus. 



The present female specimens also fall into 

 two size groups, the smaller of which is very 

 similar to Farran's small specimen. The head 

 and thorax in this form are separated by a 

 fine line (in Farran's specimen they were 

 fused) and a faint line is also seen to separate 

 the fourth and fifth thoracic segments (fig. 6). 

 Although the fifth feet are fairly well differ- 



entiated, the genital segment is undeveloped in 

 this small specimen. In the larger form (figs. 

 8-14) the head and first thoracic segment are 

 incompletely fused and the fourth and fifth 

 thoracic segments are completely fused. The 

 genital segment is well developed as ai'e the 

 fifth feet. 



Although it is slightly larger, Mori's S. spini- 

 pedata. is, in my opinion, a synonym of S. 

 ctenopus. 



Scolecithricella abyssatis (Giesbrecht, 1888) 



(Plate 16, figs. 16-20) 



Pacific records: Scott, 1909; Mori, 1937; Tanaka, 

 1937; Wilson, 1942; 1950; Anraku, 1952; Tanaka, 

 1953; Brodsky, 1955; Chiba, Tsuruta, and Maeda, 1955; 

 Nagaya et al., 1955; Chiba, 1956. 



Vessel : Station Occurrence 



Hugh M. Smith __ 94 6 females, 1.87-1.90 



mm. 



Do 144 1 female, 1.74 mm. 



Do 29 1 female, 2.21 mm. 



Do 63 1 female, 1.87 mm. 



Remarks: Some variation was noted in the 

 structure of the fifth feet of this species. Sev- 

 eral specimens did not have the small spine- 

 like protrusion near the terminal spine as 

 shown in the fifth feet figured here (fig. 20). 



Scolecithricella rillata (Giesbrecht, 1892) 



(Plate 17, figs. 1-8) 



Pacific records: Farran, 1936; Wilson, 1950; Tanaka, 

 1953. 



Vessel : Station Occurrence 



Hugh M. Smith __ 94 2 females, 1.66 mm. 



Remarks : As in the preceding species, varia- 

 tion was noted in the fifth feet of this species. 

 The terminal seta in one specimen was approxi- 

 mately twice the length of the proximal one 

 (fig. 8) while in the other specimen it was 

 somewhat shorter (fig. 4). 



Scolecithricella tenuiserrata (Giesbrecht, 1892) 

 (Plate 17, figs. 9-21; plate 18, fig. 1) 

 Pacific records: Farran, 1936; Tanaka, 1953. 



