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Xir. Studies of the Blattidae. By the late R. Shelfobd, 

 M.A. 



[Read June f)tli, 1912.] 



Plates LXXIX— LXXX. 



A REVISION OF THE GENUS ThEGAXOPTEEYX, Br., TO- 

 gether with remarks on some species of 

 Hemithyrsocera, Sauss. 



The great numbers of obscure and still undescribed species 

 of cockroaches belonging to the subfamilies JEctohiinae and 

 Pseudomopinac have convinced me that much more accu- 

 rate and detailed diagnoses of genera must be drawn up 

 if any order is to be introduced into the chaos at present 

 existing. This is a task of no mean difficulty, for whilst 

 the differences between the males of the various species 

 are patent enough, the females resemble each other very 

 closely, and the presence of characters which will enable 

 the entomologist to brigade the species into genera can 

 only be demonstrated after the most meticulous examina- 

 tion of all the external anatomy of the insects. But a still 

 greater difficulty confronts the student. The characters 

 hitherto employed to separate the subfamilies Edobiinac 

 and Fseudomojnnac are so variable and so interchangeable 

 that the allocation of a species or genus to this subfamily 

 or that is as often as not dependent almost entirely on 

 the personal opinion of the entomologist. So intimately 

 do the subfamilies interlock that more than once I have 

 considered the advisability of merging the two subfamilies, 

 and I think that I would do so had I not a lingering con- 

 viction that further study of the species, both described 

 and undescribed, will bring to light some really reliable 

 diagnostic characters. Not one of the characters usually 

 employed to distinguish the Edohiinae from the Pscudo- 

 mopinae is peculiar to the former subfamily. The transverse 

 supra-anal lamina of the male, the sparse armature of 

 the femora, the well-defined apical triangle of the wings 

 occur sporadically in the Pseud omopinae. When these 

 three important characters are shown by one species it is 

 TRANS. ENT. SOC. LOND. 1912. — PART IV. (FEB.) X X 



