Occasional Papers of the Museum of Zoologv 77 



Length. 11 mm.; width, 1.9 mm. 



Colombia : San Lorenzo. One male in forest at 4,000 feet^ 

 July 14, 1913; F. j\I. Gaige. Holotype, M. C. Z., 5,182. 



Guianonus, gen. nov. 



A genus resembling the preceding one, Arionus, in having 

 the keels narrow and in having the metatergites densely cov- 

 ered with numerous coarse granules or tubercles, of which 

 none are specially enlarged. The keels are more elevated than 

 in the other genus, standing out nearly horizontally. Keels 

 laterally fundamentally three-lobed excepting most posterior, 

 which are four-lobed. Posterior processes of keels of penult 

 tergite strongly developed, clearly surpassing the median por- 

 tion of caudal margin. At once distinguishable from Arionus 

 in the position and distribution of the repugnatorial pores, 

 which open at the distal end of the caudal lobe of keels of 

 segments five, seven, nine, ten, twelve, thirteen, fifteen, and 

 sixteen. Cauda simple, exposed from above. 



Telopodite of gonopods of male large and exposed. 



Genotype. Guianonus ectoponis, sp. nov. 



Guianonus ectoporus, sp. nov. 

 PI. 29, Figs. 207-209; PI. T,*^, Figs. 210, 211 



Dorsum dusk}- brown or chestnut, collum and head lighter,, 

 more ferruginous. Venter fulvous brown. 



Vertex of head somewhat raised as in Arionus; but the 

 area only obscurely tubercular above and below, more distinctly 

 so across its median region. 



Collum with anterior rim presenting twelve areas, the one 

 at each end of the series smaller than the others. 



Second tergite considerably wider than collum and than' 

 following tergites ; moderately bowed forward at ends, but 



