ISOPODS OF NORTH AMERICA. 



1(>3 



four hav^e the outer post-lateral an^le acutely produced beyond the 

 posterior margin of the segrnents. 



All six seg-ments of the a})domen are distinct, although the first is 

 parti}' covered at the sides 

 b}^ the last thoracic segment. 

 The sixth or terminal segment 

 is wider than long, 3 mm. : 

 2 mm., and is rounded pos- 

 teriorly with margins dis- 

 tinctly crenulate and has a 

 slight median emargination. 

 •The inner ])ranch of the uro- 

 poda I'eaches the extremity of 

 the terminal segment of the 

 abdomen. It is broad and 

 truncate posteriorly, with mar- 

 gins distinctly crenulate and 

 furnished with spines. The 

 outer branch is shorter than 

 the inner branch, is narrower 

 and more pointed at its ex- 

 tremit}'. It is also distinctly 

 crenulate and furnished with 

 spines. 



Two specimens of this spe- 

 cies were collected b}^ the U. S. 



Bureau of Fisheries steamer Alhatrfm at station 41:17, S. W. Rock, 

 Santa Barbara Islands, latitude S'- north, longitude, 6.3' west. 



DejJtJi. — 29 fathoms. 



29. Genus NALICORA Moore. 



'■•Clypeus small, peduncle of second antenni^ long; mandible weak, 

 with bidcntato cutting edge and three-jointed palp; first maxilla? very 

 large, robust, and conspicuous in situ, outer joint stout, hooked, and 

 terminated by a strong, curved si)ine in the male, continuous in con- 

 tour with the rest of the part, and with a knob-like process at its base; 

 inner joint with its tip covered b}^ a quadrate, curve-faced cap covered 

 with papilliv; second maxilla? four- jointed, first two joints stout, short, 

 third joint stout and subconical, terminal joint slender and conical, with 

 a tuft of setfe near tip; palp of maxillipeds five-jointed, slender." — 

 Moore." 



Fig. 1-15.— Tridentella virginiana. a, Maxilliped. 

 X 51|. b, Mandible, x 51|. c, Palp of mandible. 

 X 51|. d. Second maxilla, e, First maxilla 

 (outer LOBE) . X 51f. /, Frontal lamina, x 27J. 



«Bull, TT. S, Fish Commission, XX, Pt. 2, 1902, p. 169. 



