I8OPODS OF NORTH AMERICA. 575 



that of still younger female oblong, attenuated behind, with the 

 cephalon freely projecting in front, and the coxal plates occupying 

 the side-edges of the mesosome. Body of immature female, immedi- 

 ately after the metamorphosis, somewhat resembling the male in shape, 

 but having only five pairs of legs, and the metasome distinctly seg- 

 mented. Adult male linear, subcompressed, with the six posterior 

 segments of mesosome very sharply marked off from each other, 

 metasome forming a thickish, undivided piece of oval or elliptical 

 form, earning at the tip two extremely small appendages (rudiments 

 of uropoda). Color of female along the middle of the dorsal face 

 reddish brown, lateral parts whitish. Length of fully grown female 

 4 mm., that of male 1 mm." G. O. SAKS." 



99. Genus HOLOPHRYXUS Richardson. 



Body of female without any trace of segmentation. 



Abdomen abruptly narrower than thorax, unsegmented, produced 

 to a tapering extremity. Uropoda absent. Pleopods wanting. Five 

 pairs of legs present, crowded closely around the oral area. 



Five pairs of incubatory lamellae present. 



This genus differs from Dajus Kr0yer in the absence of all appendages 

 to the abdomen of the female and in lacking all trace of segmentation. 

 It differs from Notophryxm and Aspidophryxm Sars 6 in having all five 

 pairs of incubatory plates, only one pair being present in Sars's genera; 

 in having no trace of segmentation; in the shape of the oral area and 

 the position and form of the abdomen, etc. It differs from Iletero- 

 phryxus Sars' 1 in the position of the last pair of legs, which in Hetero- 

 phryxm are rather anomalous in structure, are placed at the posterior 

 extremity of the body and are adapted for clasping. It differs from 

 Branchiophryxus Caullery'' in having five pairs of legs and five pairs 

 of incubatory plates, while in Branehiophryxus there are but four 

 pairs of legs and four pairs of incubatory plates. It differs from 

 Zonophryxus Richardson e in lacking pleopoda, one pair being present 

 in Zonophryxus; in the form of the abdomen and in the general shape 

 of the body. It differs from Prodajus Bonnier^ in the form of the 

 abdomen, which is unsegmented and not bifurcate. 



Crust, of Norway, II, 1899, pp. 223-224. 



6 Idem, pp. 225-231; Norwegian North- Atlantic Expedition, Crust., I, 1885, pp. 

 136-139. 



c Challenger Report, XIII, 1885, Pt. 37, Report on the Schizopoda, pp. 220-221, pi. 

 xxxvin, figs. 8-14. 



d Journ. R. Micr. Soc. Lond., 1897, Pt. 3, p. 204; Zool. Anzeiger, XX, 1897, pp. 

 88-92. 



''Bull. U. S. Fish Comm., 1903, pp. 51-52. 



/Comptes Rend. Acad. Sci. Paris, CXXXVI, 1903, pp. 102-103. 



