162 BULLETIN 38, UNITED STATES NATIONAL MUSEUM. 



The wings are rather wider thau most species of the group. The 

 very even color and the remarkably even median lines will serve to 

 identify this form which conflicts with none at all allied to it in shape 

 of primaries. 



The Nevada specimen in Mr. Tepper's collection is somewhat darker 

 than those from Texas, and the maculation is still more completely ob- 

 solete. 



Group MESSOEIA. 



Anterior tibuTe spinose, the terminal armature heavy; the member 

 itself somewhat abbreviated, flattened and broad toward tip. The front 

 full, tuberculate, the projection centrally depressed, or knob like and 

 roughened, granulate. The thorax is moderate, usually with an indefi- 

 nite posterior tuft, occasionally with a divided anterior crest, never 

 entirely untufted. The vestiture is entirely hairy in some species, 

 mixed with flattened scales in others. The antenu;e of the male are 

 serrate, the joints strongly bristled. Primaries moderate, the apices 

 at most rectangular and often somewhat produced. The distinctive 

 feature characterizing the group is a distinct dai'k shade line through 

 the median space, and the species grouped by this character, though 

 colorational merely, are closely allied. The genitalia are all of the same 

 bifurcate type ; the lower branch is stout, straight, more or less taper- 

 ing to the tip, variable in length in the species ; the upper branch is 

 more slender, subcylindrical, curved, usually shorter than, but occa- 

 sionally exceeding the inferior branch in length. The variation in this 

 structure is so decidedly one of degree rather than kind, that the tigures 

 must be left to explain the small apparent distinctions. 



The group is divisible into two series, well distinguished at the ex- 

 tremes, but closely approaching at the middle ; yet there is little diffi- 

 culty in most cases in properly referring a species even though it is im- 

 possible for me to express the difference as briefly as I should like. 



The first series, of which hostoniensis may be considered typical, is 

 characterized by almost entirely hairy vestiture of thorax, never 

 forming a distinct divided tuft, but gathered usually into an indistinct 

 tuft posteriorly. The species are of moderate, or large size, the colors 

 generally based on a shade of gray with various admixtures of yellow 

 or red; the apices of primaries are produced, the outer margin oblique. 



The maculation in the majority of species is indistinct, the median 

 shade being often the most prominent feature. The ordinary spots are 

 obsoleteand indefinite except in extrancc and trifasciata, which, however, 

 well agree in wing form with the typical species. The secondaries ex- 

 cept in the two species above cited, and comosa and hifasciata, are white 

 in the male, dusky in the female. The four species last cited are the 

 aberrant ones of the series. The two former, however, as already 

 stated have the wing-form, while comosa has the vestiture entirely 

 hairy and hifasciata has the ordinary spots obsolete, the transverse 

 liues simple, 



