REHN AND HEBARD 



31 



Group C (gibbosus) 



Group B (atnericanus) Size medium to rather large. Pronotal 



disk with sharp lateral angles; disk proixT 

 distinctly constricted at cephaUc third to 

 fourth. Tegmina of male always with 

 distal section not covered by the pro- 

 notum. Cerci of male moderately elon- 

 gate, substyliform, acuminate, with an 

 approximately median tooth. Subgeni- 

 tal plate of male fissate. Subgenital 

 plate of female very deeply divided; 

 lateral sections sublanceolate produced 

 distad. Spurs of caudal tibiae normal. 

 Size large. Pronotal disk with distinct 

 but rounded lateral angles; disk proper 

 distinctly constricted at cephalic third to 

 fourth. Tegmina of male almost or 

 quite completely concealed under the 

 pronotum. Cerci of male very elongate, 

 corniform, tooth quite elongate and 

 relatively slender. Subgenital plate of 

 male subfissate. Subgenital plate of 

 female moderately divided; lateral sec- 

 tions rounded rectangulate. Spm-s of 

 caudal tibiae normal. 

 Size medium to small. Pronotal disk 

 with distinct but always rounded lateral 

 angles; disk gently narrowing cephalad 

 (dorsalis) or subequal and very narrow 

 {glaber and calcaralus). Tegmina of 

 male completely hidden under, or shghtly 

 projecting caudad of, the pronotum. 

 Cerci of male short, robust, acutely 

 pointed, with short stout median tooth. 

 Subgenital plate of male acutely emar- 

 ginate to subfissate {calcaralus). Sub- 

 genital plate of female moderately 

 divided (female imknown in calcaralus); 

 lateral sections moderately acute distad. 

 Spurs of caudal tibiae elongate, straight 

 for the greater portion of their length. 



Of these, group B appears to l)e more nearly the prolxible 

 ancestral type, group C being a strongly modified or rather 

 specialized phylum, which probably diverged from the primitive 

 stock before the more complex group A. The latter group 

 shows in its davisi-monticola line a complex which is very dis- 



Group D 



dorsalis 



glaber 



calcaralus 



TRANS. AM. ENT. SOC, XLII. 



