The Odonata or Dragon flies of South Afrint. 343 



MESOGOMPHUS (Porster, 1906). 



An African genus, probably also embracing some species from 

 India. No doubt it is closely allied to Onychogomplms, but the neural 

 character given in the table (p. 340) seems quite constant, and has 

 the advantage of uniting a group which is also distinguished by a 

 peculiar type of male appendages. For the moment I do not know of 

 other than geographical reasons for separating Mesogomphus from the 

 American genus Erpetogomphus. From a note by M. Rene Martin it 

 would appear that the larval type of Mesogomphus (Hageui) is rather 

 widely different from the Onycliogomplius larva and approaching 

 Gomphus ; but I have reasons to suspect that some error of observation 

 has occurred, and that Mesogomphus larvae are really of the Onycho- 

 gomphus type. 



The name as given by Forster is homonymous with a fossil genus, 

 Mesogomphus, named by Haudlirsch. But as both publications date 

 apparently from the same month and cannot be dated to a day, I 

 thought it advisable to adopt the name as given for the living group. 



Table of Males. 



1. Tips of superior appendages parallel, acute. Obscure band of base of frons 



light ochreous or absent. Obscure markings of thorax limited and 



comparatively light .2. 



Tips of superior appendages divergent, blunt and dentate. Broad black 

 band on base of frons. Obscure markings of thorax comparatively large, 

 dark brown. Costa light yellow. Pterostigma blackish brown 



M. cognatus. 



2. Pterostigma dark ferruginous. Superior appendages more robust than in 



the following species, almost straight at base, strongly curved down- 

 ward in distal fourth ; inferior appendages less than half as long as the 

 superior . . M. elpidius. 



Petrostigma light ochreous, encircled by a greyish shade. Superior 

 appendages very slender, curved downward in a gentle curve in their 

 second half ; inferior appendage more than half as long as the superior 



M. Hageni. 



Table of Females. 



1. Pterostigma dark brown .... 2. 



Pterostigma light ochreous, encircled by a greyish shade, between strong 

 black veins. No obscure markings on face and anterior surface of frons. 

 Thoi-acic markings pale reddish brown, often diffuse . . M. Hageni. 



2. Face and frons anteriorly without obscure markings. Thoracic markings 



dull reddish brown (Plate IX, fig. 3). M. elpidius. 



Face and frons anteriorly with black transverse lines. Thoracic markings 

 blackish brown to almost black (Plate IX, fig. 4) . . M. cognatus. 



