Mr. R. Shelford's Studies of the Blattidae. 311 



opinion. The West-African collections before me contain 

 quantities of examples that could be referred equally 

 well to either of Mr. Kirby's genera but I have never yet 

 seen an adult example that could be referred to them. 

 The erect pubescence of Trichomcra insignata persists in 

 many species of Gyna, and the structural differences be- 

 tween Trkhomera and Apotrogia on the one hand and 

 Gyna on the other are such as we are thoroughly familiar 

 with in the larvae and adults of other genera of Blattidae. 

 The species of Gyna can be divided into two sections ; 

 in one section the pronotum is smooth and nitid, rich 

 castaneous in colour, with ochreous margins ; in the other 

 section the pronotum is testaceous but the disc is occu- 

 pied with a piceons or castaneous lyrate marking that 

 under the lens presents an appearance as if it had been 

 chiselled out of the surface of the pronotum ; the form 

 and extent of the marking is very variable and presents 

 few characters of importance in classifying the species. 

 G. hyalina may be regarded as intermediate in character 

 between the two sections of the genus and G. capucina 

 in its pronotal colour and sculpture occupies an isolated 

 position. The distance apart of the eyes on the vertex 

 in the male is a character of some importance and full 

 use has been made of it in the following synoptical key. 

 Another character that can be employed, though with 

 caution, to separate species with lyrate markings on the 

 pronotum, is the presence or absence of a circular rufescent 

 macula on the discoidal field of the tegmina. The pos- 

 terior part of the pronotum and the tegmina in some 

 species (e. g. G. maculijjennis and G. fervida) present a 

 peculiar mottled appearance, which is due to the irregular 

 deposition of opaque testaceous pigment between the two 

 layers of chitin, the chitin itself being quite transparent. 

 De Bormans (Ann. Soc. ent. Belg., xxv, p. 21, 1881) 

 figures the ootheca of G. caffroruni ; from his figure and 

 description I believe that the ootheca is merely a mem- 

 branous sac and that the species of this genus are vivi- 

 parous or ovo-viviparous like the Epilamprinae whose place 

 in Africa is so largely taken by the species of Gyna. Karny 

 (Jenaische Denkschriften, xiii, p. 382, 1908) has sug- 

 gested that the ulnar rami of the wings in a species 

 described by him as Gyna stridulans have the power of 

 producing a rattling noise when the insect flies. He sees 

 a resemblance between this part of the wing in the cock- 



