1S98.] 59 



consequently is invisible in the cephalad aspect of the specimen. The 

 only exception to this formation at present known to me occurs in 

 C.prasinula, in which the teeth are decumbent as well as divergent, and 

 therefore are always visible in the cephalad aspect of the specimen, at 

 least in their distal half. It frequently happens that the anal tube is 

 raised, so that its posterior face is horizontal, in which case, of course, 

 the teeth are quite exposed. The function of these teeth appears to 

 be that of keeping the sedeagus in place. 



The differential characters of the males of the species which I 

 have examined are given below ; I am not able to identify female 

 specimens taken apart from the males. 



1. Scutellum, beyond the side keels, with a black subtriangular patch on each side. 



Apex of style obliquely truncate, with both the upper and lower angles pro- 

 duced into a sharp triangular tooth dorsata, n. sp. 



Scutellum entirely pale 2. 



2. Posterior face of the anal tube with a very small, sharp, recurved tooth or hook 



at each lower corner glaucescens, Fieb. 



Posterior face of the anal tube unarmed at the lower corners 3. 



3. Teeth of the anal tube curved, directed obliquely outward, forward, and down- 



ward, their distal half, therefore, visible in the same aspect as the posterior face 



of the anal tube prasinula, Fieb. 



Teeth of the anal tube straight, directed almost horizontally cephalad, and, 

 therefore, not visible in the same aspect as the posterior face of the anal tube... 



4. 



4. Periphery of the pygofer, in the cephalad aspect, suborbicular... 



smaragdula, Stal. 

 „ „ „ „ „ „ ti'ansversely elliptic .. 



unicolor, H.-S. 



C. DORSATA, n. Sp. 

 $ . Abdomen above black, the sides narrowly yellow. Pygofer yellow, a little 

 darker above, the upper notch wide, rounded-triangular, reaching from side to side 

 of the segment, and extending cephalad almost to the hind margin of the last dorsal 

 segment, the lower notch angular, with straight sides, and a small, almost semi- 

 circular, excavation in the middle, viewed from the side the hind margin passes 

 obliquely and almost in a straight line from the hind margin of the last dorsal 

 segment to the commencement of the lower notch. Contents of the genital aperture 

 brownish-yellow. Anal tube with the aperture transversely elliptic, its lower edge 

 much widened and produced on each side into a large, blunt, triangular tooth, the 

 teeth proper nearly straight and directed almost horizontally cephalad. Genital 

 aperture (or mouth of the pygofer) somewhat triangular, with widely rounded angles. 

 Styles gradually narrowed from base to apex, nearly straight, their apices obliquely 

 truncate, with both the upper and lower angles produced into a sharp triangular 

 tooth. Scutellum with a black subtriangular patch on each side beyond the side 

 keels. Otherwise like C glaucescens. 



