November 18(14. 



rsrcHE. 



165 



The two forms diflei" oiilv in the 

 degree of development (or abortion) of 

 wings and pronotiim and for this reason 

 are believed by some to be forms of one 

 dimorphic species. For this reason I 

 here treat them together. 



Lateralis is distingnished from polv- 

 morp/ia by the presence of fully devel- 

 oped wings and nsuallv hv a somewhat 

 longer pronotum. The variation in 

 these structures and their relative pro- 

 portions with regard to other parts of 

 the body and to eacii other will be best 

 observed in the measurements here 

 given. I have one specimen, a ^f ■ 

 in which tiie pronotum does not pass 

 the hind femora Init the wings extend 

 2.5 mm. beyond it, thus lieing inter- 

 mediate in character between the two 

 forms. This specimen ma}' be regarded 

 as either a lateralis with unusually 

 sliort pronotum, or a reveisional foly- 

 morplia, — I am disposed to think that 

 the former view- is the more correct in 

 this case, for the reason that the prono- 

 tum is of ver\' variable length in Ixjth 

 forms, and its apex is frequently twisted 

 or distorted in one way or another, 

 while the wings seem to be relativelv 

 quite constant in length. 



While I am -h\ no means convinced 

 ihiit lateralis -\- lateralis \\'\\\ not pro- 

 duce polvmorpka, or poly Dior pJia-\- 

 poly7>iorpha will not produce lateralis 

 {i. c, that the two forms are not one 

 species) I have given each specific rank 

 here for the reason that, whether thev 

 are distinct species or dimorphic forms 

 of one, both names will be retained, as 

 they properly should be, to distinguisii 

 them. And as the\- liave hitherto l)een 



observed to mate true they mav best be 

 regarded for the present as incipient 

 species. 



Tiie reasons pro and con may be 

 summed up as follows, structural char- 

 acters only being considered : — 



1st, in flavor of specific distinctness — 



They have been observed many times 

 to mate true and not cross with each 

 other. 



Intermediate specimens are very 

 scarce. 



Both forms are tolerablv common. 



2nd, in favor of dimorphism — 



Cases of reversion are common in 

 other species of the family, witli or 

 without intermediate forms. 



Cases of dimorphism are \-erv com- 

 mon in other species of the faniih'. 



Variations in length of tegmina and 

 wings are usually of little or no impor- 

 tance in other members of tiie family. 



Variations in length of pronotum in 

 this subfamilv correspond to variations 

 in length of tegmina in others. 



Cases of reversion occur in this sub- 

 family. 



Cases ot tiinKnpiiism occur in this 

 subfamily. 



In such cases the wings are usually 

 shortest proportionally in specimens 

 with the shortest pronota and vice 

 versa. 



Intermediate forms occur, having 

 pronotum of one form and wings of 

 the other. 



Similar forms occur in other species 

 of the genus. 



In the short-wiiiged form tke end of 

 the pronotum is especially subject to 

 distortions of one sort or anotlier. 



