COPEPODS FROM EQUATORIAL WATERS OF PACIFIC OCEAN 



211 



Vessel: Station Occurrence 



Hugh M. Smith _. 144 1 female, 1.08 mm.; 



1 male, 1.17 mm. 



Do 178 4 females, 1.05-1.10 



mm.; 4 males, 

 1.0-1.27 mm. 



Do 31 present. 



Sinuujer 34 3 females, 1.02-1.10 



mm. 



Remarks : Because of the difficulty encoun- 

 tered in identifying this species, I have included 

 several figures of the female and a figure of 

 the fifth feet of a specimen that I consider to 

 be the male of this species. Giesbrecht and 

 Schmeil (1898) stated that the second basal 

 segment of the first maxilla of the female has 

 5 setae. The present specimens have 3 setae 

 on this segment. Although these authors indi- 

 cated that the male of this species is question- 

 able, they gave the length as 1.45 mm. as com- 

 pared to 1.15 mm. for the female. The present 

 males are also larger than the females. 



Scolecithricella marginata (Giesbrecht, 1888) 

 (Plate 18, figs. 2-9) 

 » Pacific records: Scott, 1909; Wilson, 1942. 



Vessel : Station Occurrence 



Hugh M. Smith __ 144 2 females, 1.05 mm. 



Do 178 2 females, 1.00, 1.02 



mm. 



Remarks : The small size and fifth feet (fig. 

 9) serve to identify this species. 



Scolecithricella tropica n. sp. 

 (Plate 18, figs. 10-18) 



Vessel: Station Occurrence 



Hugh M. Smith .^ 94 4 females, 1.22-1.30 



mm. 



Do 132 5 females, 1.15-1.27 



mm. 



Do 178 2 females, 1.13, 1.14 



mm. 



Description: Of the 11 specimens of this 

 species examined, none was intact. The fol- 

 lowing description is based, therefore, on sev- 

 eral specimens and even with these a discus- 

 sion of certain appendages will not be possible. 



The cephalothorax is considerably longer 

 than the abdomen, the ratio of these two body 

 parts is approximately 4.4: 1.0 (figs. 10, 11). 



The posterior thoracic border has a well-defined 

 indentation at a point ju.st anterior to the apex. 

 The genital segment is longer than the com- 

 bined lengths of the next 2 segments. The ros- 

 tral filaments are long and apparently not ar- 

 ticulated to the base (fig. 12). 



The first maxilla (fig. 13) has the following 

 number of setae: 2 on the second inner lobe, 3 

 on the third inner lobe, 5 on the second basal 

 segment, 8 on the endopod, and 6 on the exo- 

 pod. 



The terminal portion of the second maxilla 

 (fig. 14) has 5 sensory and 3 worm-like ap- 

 pendages. 



The first pair of feet (fig. 15) has a 3-seg- 

 mented exopod and 1-segmented endopod. A 

 group of small spines is present on the second 

 basal segment near the distal margin. The exo- 

 pod of the second pair of feet consists of 3 seg- 

 ments and the endopod of 2 segments (fig. 16). 

 Two spines are present on the surface of the 

 first exopodal segment, a group of large and 

 small spines on the second segment and three 

 groups of spines on the third exopodal segment. 

 Five large and 2 small spines are present on 

 the second endopodal segment. 



As in certain other species of Scolecithricella, 

 the fifth feet are variable. Most of the speci- 

 mens examined have 2, approximately equal, 

 terminal spines (fig. 17) but at least 2 speci- 

 mens were observed to have 3 on one side and 

 2 on the other (fig. 18). 



This species is distinguished from other spe- 

 cies of Scolecithricella by the indentation on 

 the posterior thoracic margin and the structure 

 of the fifth feet. 



Remarks: An undissected female from Sta- 

 tion 94 was selected as the holotype (U.S.N.M. 

 No. 104, 416). This specimen and 6 paratypes 

 (Nos. 104, 417-104, 419) have been deposited 

 in the U.S. National Museum. 



Scolecithricella sp. 

 (Plate 19, figs. 1-5) 



Vessel: Station Occtirrence 



Hugh M. Smith __ 144 2 males, 1.20, 1.22 



mm. 



Remarks: Two male specimens which are 

 apparently referable to the genus Scolecithri- 



