62 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.86 



tending obliquely downward in an almost straight line and with a 

 narrow rim reaching from around the anterior corner to the posterior 

 corner, which is almost a right angle and not conspicuously clasping 

 the side of the body and lacking pronounced striations. 



Segments 2, 3, and 4 forming a moderately constricted neck, the 

 posterior margin on segment 4 five-sevenths as wide as the first seg- 

 ment at its broadest part. Segments 2 and 3 flat, without transverse 

 constrictions ; segment 4 with a constriction behind which the surface 

 is more convex. 



Anterior division of the subsequent segments quite convex; a 

 series of shallow channels along its posterior part, the channels less 

 than twice as long as broad, smooth within, separated by fine, raised, 

 beaded lines; anterior part of subsegment coarsely reticulated; pos- 

 terior subsegment abruptly raised from the constriction considerably 

 higher than the anterior subsegment, strongly convex ; dorsal surface 

 appearing smooth and shining but with correct magnification and 

 lighting numerous short, irregular, impressed lines appear, which, 

 when well developed, form reticulations having meshes longer than 

 broad. A segment from the middle of the body is shown in figure 19, 

 1). Pores beginning on segment 5, placed on a very slight swelling 

 high on each side; on the anterior segments the pore is in front of 

 the middle of the subsegment, but farther back it is at the middle. 

 Sides below the pores finely striate longitudinally, the striae of 

 the anterior segments farthest up the sides. 



Antepenultimate segment less convex than preceding but more 

 so than the nearly flat penultimate segment. 



Last segment longer than tlie two preceding segments together; 

 posterior margin broadly rounded, with four apical setae and another 

 seta on each side. 



Anal valves strongly inflated; margins meeting in a narrow, shal- 

 low groove. Preanal scale over three times broader than long ; front 

 margin rounded more than the back margin; tab process on either 

 side large. 



Gonopods as shown in figure 19, c. 



Segment 6 of male with pleurae not produced backward ; segment 

 7 with the opening for the gonopods U-shaped, its margin strongly 

 elevated. 



LEIODERE NANA, new species 



FiGtnsE 20 



Numerous specimens, including the male type, U.S.N.M. no. 1314, 

 vrere collected between Vallejo and Cordelia, Calif., January 4, 1928, 

 by Dr. O. F. Cook, who also collected a male and two females at 

 Cordelia on February 20, 1929. 



