Occasional Papers of the Mitseiini of Zoology 73 



Zigwadesmus guiananus, sp. nov. 

 PI. 27, Figs. 189-193; PI. 28. Fig. 195 



Color alcove and over sides brownish chestnut to chocolate, 

 the venter more fulvous. Keels and an immediately adjoining 

 portion of tergite above them yellow, as is also a narrow 

 median dorsal longitudinal stripe which is interrupted on ante- 

 rior part of each prozonite. Legs light brown. Xo pale spot 

 on each side of prozonite such as characterizes brunneus. 

 Antennae darker brown. 



Head wideh- and deeply excavated from base of each 

 antenna caudad, an elliptic, somewhat elevated organ lying in 

 this excavation, as in the genotype. 



Keels of second, third and fourth segments normally devel- 

 oped. Each with a low tooth at anterior corner, which is bet- 

 ter developed than in brunneus. Caudal angle of fourth keels 

 more broadly produced than in brunneus. Keels caudad of 

 the fourth narrow and thick, appearing as simple bulgings of 

 the tergite with a margining sulcus ; caudal angles produced 

 in all. l)Ut keels in anterior portion becoming low and obsolete, 

 though in general a little better developed than in the genotype 

 and inserted a little higher on the sides of the segments. Porif- 

 erous process set off by a sharp sulcus from remaining por- 

 tion of keel, its ectal face elongate elliptic. (PI. 27, Figs. 189- 

 191.) 



The conical tubercles at distal end of cauda are shorter and 

 more rounded than in brunneus and are not directed somewhat 

 ventrad of caudad as in that species. (See PI. 27, Fig. 193, 

 and PI. 28. Fig. 195.) 



The anal scale differs from that of brunnetts in having the 

 caudal margin between setigerous tubercles rounded, instead 

 of angular, and not surpassing the tubercles. (PI. 27, Fig. 

 192.) 



