38 PKOCliEDIXC.S OY THE XATIOXAL MUSEUM. vol. 6C. 



the middle of the keel, the pore body lying less than once and a half 

 from the margin between teeth, often scarcely more than its diam- 

 eter (see pi. 15, fig. 5). Tubercles of sternites of normal form. The 

 anal valves are strongly margined, the elevated rims being smooth. 

 The setigerous tubercles are of moderate size, the anterior the larger, 

 and are contiguous with but both distinct from the marginal rim. 

 Margin of sides of last tergite scarcely elevated into a true tubercle 

 to bear the upper lateral seta (see pi. 15, fig. 6). Tubercles of anal 

 scale large, distally truncate (pi. 15, fig. 7). The gonopods when in 

 place cross each other and fit into the depression on the sixth seg- 

 ment, as usual. The accessory branch is broad, but is narrower than 

 the middle part of gonopod, distally rounded (pi. 15, fig. 8). 



Length, 78 mm. ; width, 13.5 mm. 



Locality. — Costa Rica: One male (C. Bergdorf and P. Schild, Ace, 

 38,962, U.S.N.M. 



Type.— Cat No. 843, U.S.N.M. 



85. NYSSODESMUS MIMUS, new species. 



Plate If), figure.s 9-11. 



This species differs from the other two here described in having 

 the dorsum between the keels uniform brown, the keels entirely' 

 yellow. Head brown, without a yellow area above. Last tergite 

 brown at base above, with distal half of the caudal process yellow. 

 Head less elevated each side of the vertigial furrow than in the 

 preceding species and the antennal ridge less developed. Lat- 

 eral margins of collum with six or seven low, nearly uniform, blunt 

 crenalions. Surface depressed transversely between anterior and 

 posterior borders and across base of keel. Surface in general densely 

 granular; a series of small tubercles across anterior border; the 

 nongranular, somewhat elevated marginal thickening of the posterior 

 border divided into tuberclelike segments by longitudinal furrows 

 or depressions. The granulation of the surface of metazonites more 

 pronounced and uniform than in nicaraguaruiis. The posterior border 

 divided into areas by longitudinal sulci, as in the latter species. 

 Anterior margin of keels oblique in about same degree as in that 

 species ; lateral margins weakW undulate, excepting notch at middle, 

 which is deeper than in nicaraguanus; caudal processes of posterior 

 region a little less acute. The pore body is a little nearer the margin 

 at the median notch, mostly a little more than once and a half, but 

 less than twice its diameter removed (pi. 15, fig. 9). 



As in nicaragumvus^ the caudal tubercle of the anal valves is fused 

 with the marginal elevated rim, the larger anterior one remaining 

 distinct. Anal scale with tubercles large, the caudal margin between 

 them angled; lateral margin concave instead of a little convex 

 (pi. 15, fig. 10). 



