448 GEOLOGICAL SURVEY OF THE TEERITOEIES. 



Dimensions. — $ , leugth, 2 inches; elytra, 1.95 inclies. <? , length, 1.6 

 inches; elytra, 1.74 inches; posterior femora, 1 inch; posterior tibiae, .9 

 inch. 



Southern Illinois; Kansas, (Thomas;) Tennessee, (T. Eogan, esq.) 



There has been much confusion in regard to theA. Americanum., (with 

 which the present species has, doubtless, been confounded,) notwith- 

 standing its large size, distinct markings, and the very full description 

 given by Drury as early as 1770, with an accompanying colored figure. 

 The markings and carvings of the two species are nearly exactly alike; 

 but the general or ground colors are very diiferent, the one being a deep 

 vermilion or purplish-red, and the other a dull yellow, or light brownish- 

 yellow. But, in addition to this difference, I am satisfied, after a close 

 observation of the two in Illinois for several years, that they are differ- 

 ent species from another fact : the A. cimhiguum always appears in the 

 spring, in April or May, while the other never appears earlier than the 

 middle of July; and from quite a number of specimens of each sent me 

 the past season from East Tennessee, by Theophilus Eogan, esq., of Eus- 

 sellville, 1 am satisfied the same thing occurs there. The A. Americanum 

 made its appearance in Washington City this season in the latter part 

 of August and first of September ; but not a specimen of the other species 

 was to be seen among them. The two species differ considerably when 

 on the wing, the wings of the A. Americanum having a peculiar silvery 

 appearance not observable in the other. The larvte also are different, 

 those of the former being reddish -brown, while the latter is greenish. 



De Geer (Mem. Ins., Ill, PI. 40, Eig. 8) figures probably a specimen 

 of my amMgimm, which he names A. flavo-fasciattim ; but Serville's 

 description under this name applies to an entirely different species. 

 Olivier's A. viitaium, (Encyc. Method Ins., YI, 221,) which he gives as 

 synonymous with De Geer's species, is also a different insect. De Haan, 

 who received specimens from Tennessee, through Dr. Troost, undoubt- 

 edly of my amhiguuon, says (Bijdr. Kenn. Orthop., 143) that A. carneipes, 

 Serv., is but a variety of A. flavo-fasciatimi, to which he refers his speci- 

 mens, thus evidently making two mistakes. Westwood, in his edition 

 of Drury, gives the name Lociista. tartarica to his figure of this species, 

 thus identifying it with Grylhis tartaricus, Linn., one of the destructive 

 oriental species. 



Professor T. Glover figures A. Americanum under the name of -A. r^is- 

 iicum, probably after Burmeister, whose description evidently applies to 

 A. alutaceitm, Harr. Walker (Cat. Dermap. Salt., Ill, 550) transfers A. 

 Americanum to his new genus, Cyi-tacantJiacris, to which, if correct, v^^e 

 should also transfer the other species. But his only generic descrip- 

 tion is, that the posternal spine is bent-or curved obliquely backward 

 upon the mesosternum, adding that it corresponds with Serville's Div. 1 

 and Burmeister's Div. 2A of Acridium. Now Serville states as one of 

 the chief characters of his Div. 1 that "the subanal plate of the male 

 is long, triangular, entire, and pointed," while both these species have 

 the subanal plate very distinctly and strongly notched, which places it 

 ■ in his second division, subdivision qq. 



In this state of confusion I have concluded to give a new name to 

 the yellow species, as it does not appear to have betn distinguished 

 from A. Americanum., although it has doubtless been referred toby some 

 of the authors mentioned. 



A. frontalis, noy. sp. PI. II, fig 1. 



Vertex sub-conical, small size; elytra and wings not passing the 

 abdomen. General color green. Closely allied to A. imilineatum, Walk. } 



