BY R. J. T1LLYARD. 365 



stated that T regard R as a single elongated main stem, from 

 which a series of primary branches comes off anteriorly, meeting 

 the costal border. In counting these branches, I do not include 

 the small fork or forks that may be present near the tip of this 

 main stem, because I consider these to be only secondary fork- 

 ings, of the same nature as the branches of some of the forkings 

 of the primary branches themselves. To take an example : -by 

 reference to Text fig. 29c, I should say that Escala circumducta 

 had a radius with thirteen primary anterior branches, the first 

 nine of which are simple, the next four themselves branched or 

 forked. The last primary branch arises just above the forking 

 of M. To make this quite clear, I should add the phrase " ex- 

 cluding the distal forked end of the main stem," which, as will 

 be seen from the figure, divides into three very short veins. 

 This method of description has been followed throughout the 

 paper, and I trust that it will be quite plain. 



As regards the naming of the wing-areas, the rule in the 

 Comstock-Needham System is that each area should be named 

 from the vein that bounds it anteriorly. This is awkward for the 

 Blattoidea, since it makes the area in which all the branches of 

 R lie, the subcostal area. But it is better to put up with this 

 than to make one rule for the Blattoidea and another for those 

 insects in which the branches of R are posteriorly placed. As 

 regards the area served by the branches of Sc, the rule makes it 

 quite clear that the whole area between the costal border and 

 the main stem of 8c must be the true costal area, and will con- 

 tain within itself all the branches of Sc. Hence a new name is 

 needed for the clear basal portion of the costal area which is of 

 such value as a generic character. This I propose to term, in 

 full, the humeral 2}ortion of the costal area, a term which may 

 conveniently be shortened to humeral area, provided it is under- 

 stood that it is always part of the costal area proper. When Sc 

 becomes a single straight vein, then the humeral area and the 

 costal area coincide, as in iSamaroblatta, n.g. In some cases, as 

 in Triasioblatta insignita, n.g. et sp. (Text-fig. 32), the humeral 

 area has its costal border strengthened, and this strong border 

 is continued beyond the first branch of Sc. 



