ISOPODS OF NORTH AMERICA. 575 



that of still youMocr female oblonu-. attemiuted hehiiul, with the 

 ccphaloii freely project ini;- in front, and the coxal plates occupyiii>^- 

 the side-edg-es of the ines()soin(\ Body of immature female, immedi- 

 ately after the metamorphosis, somewhat reseml)liiii>- the male in shape, 

 but liavino- only tive pairs of lejjfs. and the metasome distinctly seg- 

 mented. Adult male linear, su))eompressed. with the six posterior 

 seo-ments of mesosome yery sharply marked ott' from each other, 

 metasome formino- a tliickish. undiyided piece of oyal or elliptical 

 form, carryino- at the tip two exti-emely small a})pendao-Gs (rudiments 

 of uropoda). Color of female aloiio- the middle of the dorsal face 

 reddish brown, lateral ])arts whitish. Leno-th of fully grown female 

 4 nun., that of male 1 mm." — (i. O. Saks." 



99. Genus HOLOPHRYXUS Richardson. 



Body of female without any ti'ace of segmentation. 



Abdomen abruptly narrowei' than thorax, unsegmented. produced 

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

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



Fiye pairs of incu])atory lamelhe present. 



This genus differs from Dnjiix KroA^er in the absence of all appendages 

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

 It differs from JSoioplti'ti.nts. and Axi>l<l<q>ln'y.ru>< Sars'' in haying all tive 

 pairs of incubatory plates, only one pair l)eing present in Sars's genera; 

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

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

 plwyj'ux Sars' in the position of the last pair of legs, which in JL4er<>- 

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

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

 Bi'ducIuopJiryd'us Caullery'' in having five pairs of legs and five pairs 

 of incubatory plates, while in liiumch/ojtlwy.nts there are but four 

 pairs of legs and four pairs of incu))at()ry i)lates. It differs from 

 Zonophryxus Richardson' in lacking pleopoda, one pair being present 

 in Z(>noj>hry.fus; in the form of the abdomen and in the general shape 

 of the ))ody. It differs from Prodajns Bonnier-^' in the form of the 

 abdomen, which is unsegmented and not bifurcate. 



" ("rust, of Norway, II, 1899, pp. 228-224. 



''Idem, pp. 225-231; Nor\ve<iiaii North-Atlantic Expedition, Cru.st., I, 1885, pp. 

 l.'W-139. 



« Challenger Report, XIII, 1885, Pt. 37, Report on tlie Sciiizopoila, pp. 220-221, pi. 

 xxxviii, figs. 8-14. 



'Mourn. R. Micr. Soc. Loud., 1897. Pt. 3, p. 204; Zool. Anzei.i^'cr, XX, 1897, pp. 

 88-92. 



'Bull. V. S. Fish Coinni., 190;5, pp. 51-52. 



.?'Conipte.sRend. Acad. Sci. Paris, CXXXVI, HtO:',, pp. 102-lO.S. 



