The Odonaia or Dragonflies of South Africa. 343 



MESOGOMPHUS (Forster, 1906). 



An African genus, pro))ably also embracing some species from 

 India. No doubt it is closely allied to Onychogonifhus, 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 geogi'aphical reasons for separating Mesogonvphus from the 

 American genus Erpetogomphus. From a note by M. Keni' Martin it 

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

 widely different from the Onychogomphus larva and approaching 

 Oomphus ; 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, 

 Megogoniphus, named by Handlirsch. 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 thora.v 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. Ptercstigma blackish brown 



M. coynatus. 



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 moi-e than half as long as the superior 



M. Hageni. 



Table of Females. 



1. Pterostigma dark brown 2. 



Pterostigma light ochreous, encircled by a gi'eyish shade, between strong 

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

 Thoracic markings pale reddish brown, often diffuse . M. Hageni. 



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



dull reddish bi'own (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. 



