G54 Mr. R. Shelford on the Studies of the Blattidat. 



fallax, Sauss., mass/iac, Sauss. and Z., sabauda, Giglio-Tos), 

 and when in this form the type of wing-structure approaches 

 that of Blattclla very closely. The other extreme causes 

 the wing-structure to resemble that of Theganopteryx (e. g. 

 circumcincta, R. and F., itcavci, sp. n.) and every gradation 

 may be found between the two extremes if a large enough 

 number of species is examined. As a matter of fact the 

 apical triangle is not a character of the first importance, 

 its form appears to be correlated with the relative length 

 and breadth of the wing, which again depends largely on 

 the body-length ; the longer the wing the narrower and 

 the more ill-defined the apical triangle is a general rule, 

 with of course many exceptions, and the converse holds 

 true also. 



The species described below are either new to science or 

 else of considerable interest as having long occupied very 

 precarious situations in classification ; the synonymy of 

 H. circumcincta, R. and F., is a good example of the latter. 



Finally I give a list of the species of Hemithyrsocera, and 

 it will be noted that I have transferred to it some species 

 from the old " portmanteau " genus Phyllodromia, Serv., 

 and also some species which in my " Genera Insectorum " 

 memoir (Ectobiinae) I placed in Theganopteryx. Concern- 

 ing these latter species I shall doubtless be accused of 

 chopping and changing, but in palliation of my offence can 

 only urge that my predecessors appear to have held as 

 vague and uncertain views of the limits of the two puzzling 

 genera discussed in this paper as I did until recently. It 

 was not till I had critically examined a large number of 

 type-specimens that I was able to gain a clear picture of 

 the two genera. That being done I now hope that the views 

 expressed here are quite final and decisive, and that there 

 will no longer be confusion between the two genera. 



A word may be said in passing on the genus Pseudectobia, 

 Sauss. Originally erected to include the species with a 

 conspicuous apical triangle and multiramose vena ulnaris 

 alarum as opposed to the simple ulnar vein of Theganopteryx, 

 it gradually came to include a number of most diverse 

 species and its boundaries became so elastic that they 

 could not be defined with accuracy. Later, de Saussure, 

 in his work on the Orthoptera of Madagascar, regarded 

 Pseudectobia as a mere sub-genus of Thegiotopteryx, but to 

 adopt this view involves the removal of the type species 

 P. luneli, Sauss., from the genus ! P. luneli is unfortunately 



