234 NEOTROPICAL PSELAPHIDAE 



swollen, fourth segment irregularly transversely flattened at base on dorsal face 

 and the external face angulate-produced at middle ; clypeus extended apically 

 in an acute-pyriform outline with sharp apex; interantennal line medianly 

 concave, with a small cusp just posterior to the concave area, a pair of small 

 median tubercles in a depression between the eyes. 



Group II 



Head as long or much longer than wide 2 



Head distinctly much wider than long, and distinctly wider than pro- 



notum 6 



2. Clypeus with a posteriorly curved, pointed horn 3 



Clypeus with either a simple tubercle or a carina 5 



3. Interocular excavation not limited apically by a carina; 2.4 mm 



hiatusus 



Interocular excavation sharply limited apically by an elevated carina 

 or carinated ridge 4 



4. The limiting carina entire and simple between the antennal bases; 



2.1 mm bubalus 



(Not to be confused with Arthmius bubalus, s.s.) 

 The limiting carina between antennal bases strongly ciliated and 

 medianly interrupted ; 2.4 mm grouvellei 



5. Clypeus with a simple tubercle; 2.3 mm centralis 



Clypeus with an obtuse carina brevispinus 



6. Head, including eyes, one-fourth longer than head from occiput to 



apex of clypeus, and because the antennal tubercles are externally 

 produced, the head through the tubercles is distinctly wider than 

 total head length; vertex with a deep, transverse excavation in the 

 shape of a dumbbell, with a small acute median horn at center of 

 excavation which opens apically as the deeply arcuate inter- 

 antennal line; 1.8 mm. intermediate trochanters simple, .hetschkoi 

 Intermediate trochanters provided with a dense brush of short setae; 

 2.4 mm transversalis 



Transversalis and hetschkoi are separable on a number of points in addi- 

 tion to the intermediate trochanters. The former has obtuse but well developed 

 apical pronotal angles, sides of pronotum nearly straight posterior to the ab- 

 ruptly formed apex and deep lateral pronotal sulci. The latter has a cordiform 

 pronotum with insensibly formed apical angles, rounded sides and poorly formed 

 lateral sulci. 



The ambiguously isolated mashona Raffray of Southern Rhodesia is placed 

 by Raffray (1897) next to hetschkoi. 



There is another species which is placed in this group. Raffray (1908a) 

 described Arthmius bruchi as belonging to the subgenus Syrbatus, but stated 

 that it was nesLr Arthmius sits (Schaufuss) and Arthmius carinatus (Schaufuss). 

 Both of the latter are true Arthmius without lateral pronotal sulci, the former 



