2 PEOCEEDINGS OF THE NATIONAL MUSEUM vol. «0 



distinctly separated in the male than in the female. The outer 

 rami of the second antennae consist of T segments. 



The mandible, the maxilla, and the first maxilliped of the adult 

 male are greatly reduced. Tlie terminal part of the second maxil- 

 liped consists of five short segments which are reflexed on the 

 second basal segment in both sexes. 



The inner ramus (endopodite) of the first pair of swimming legs 

 consists of one segment, that of the second pair of two segments, 

 and those of the third and fourth pairs of three segments. The 

 outer ramus (exopodite) of the first to fourth pairs of swimming 

 legs is three-segmented. The fifth pair of legs is absent in the 

 female, but large and greatly modified in the adult male. 



SENECELLA CALANOIDES Juday 



Senccella calanoides Jtjday, Science (n. s.), vol. 5S, 192.3, p. 205. 



One female has been selected as the type of the species and has 

 been given Cat. No. 57707, U.S.X.M. There are in addition 10 para- 

 types, females, Cat. No. 57708, U.S.N.M., and II male specimens. 

 Cat. No. 57709, U.S.N.M. 



Characters of female. — In a dorsal view (pi. 1, fig. 1) the body 

 is evenly rounded in front, but it is leather sharply truncated pos- 

 teriorly; in a side view (pi. 1, fig. 2) the ventral margin is nearly 

 straight, while the dorsal margin is evenly rounded both anteriorly 

 and posteriorly. The last segment of the thorax bears only mod- 

 erate sized lateral expansions. 



The abdomen is made up of four segments. The first or genital 

 segment is nearly as long as the other three combined and is some- 

 what dilated on the ventral surface, with the genital opening ap- 

 proximately in the middle of the segment. Caudal rami less than 

 twice as long as broad. More than 200 females were examined for 

 ovisacs, but none was found: it seems probable therefore that the 

 eggs are not carried during the period of incubation in this form. 



Tlie first antenna (pi. 1, fig. 3) is made up of 25 segments, the 

 eighth and ninth being somewhat coalesced. "When reflexed, the 

 antenna reaches the end of the first segment of the abdomen. Each 

 antenna bears seven sensory appendages, one each on the second, 

 fifth, ninth, twelfth, fourteenth, nineteenth, and twenty-fifth seg- 

 ments. 



The second antenna (pi. 1, fig, 4) is medium sized; the inner 

 ramus is somewhat broader than the outer. The outer ramus is made 

 up of seven segments, of which the second and the seventh are the 

 longest; the inner ramus is two-segmented. 



The mandible (pi. 1, fig. 5) bears only a moderately expanded 

 masticatory part ; the cutting edge is armed with several teeth. 



