10 AMERICAN ENTOMOLOGY. 



Ohs. This genus was established by Fabricius under the name 

 whicli, with Thunberg, I have adopted. Linne included the 

 species in his genus Gryllus. Lamarck distinguished them by 

 the name of Acheta, and Latreille by that of Tetrix. The species 

 are nearly all small, and several are common. They may be very 

 readily distinguished from " grasshoppers " of other genera, by 

 the remarkable elongation of the thorax, which is continued 

 backward so as to cover the abdomen wholly or in great part. 



AcRYDiUM ORNATUM. — Specific character. Whitish ; beneath 

 fuscous ; thorax nearly as long as the wings, spotted with black. 



Desc. Head blackish ; vertex with an elevated longitudinal 

 line, which extends down over the front where it is grooved, but 

 this groove does not reach the acute ridge which divides the 

 vertex from the front ; thorax flattened, somewhat granulated and 

 whitish, laterally projecting a little over the origin of the heme- 

 lytra, a slightly elevated longitudinal central line, and two abbre^ 

 viated oblique elevated lines near the head ; a velvet black spot 

 each side over the tip of the hemelytra : pleura, hemelytra and 

 pectus black-brown. 



Length to the tip of the wings, half an inch. 



Ohs. I am indebted to Mr. Lesueur for this interesting species, 

 which he caught at Kaighn's Point, in the vicinity of Philadel- 

 phia. The insects of this genus vary much in their sculpture, 

 size and color, which renders it difficult to distinguish the species, 

 of which we seem to have several. In the above description I 

 have purposely avoided a minute detail of colors and markings, 

 noting such only as will probably prove to be permanent, or 

 nearly so, and characteristic of the species. 



The left hand figures of the plate ; natural size and magnified. 



AcRYDiUM LATERALE. — Specific character. Pale brownish- 

 testaceous, with a lateral broad fuscous line ; thorax shorter than 

 the wings. 



Desc. Vertex with an elevated longitudinal line, commencing 

 near the tip, and extending down over the front, where it is 

 canaliculate the whole length, and terminating beneath the an- 

 tennae : antennae reddish-brown, blackish at tip : thorax flattened, 

 with small longitudinal lines or wrinkles, and a more obvious, 

 continuous, elevated central line, extending the whole length : 

 wings brown on the anterior margin towards the tip, and extend- 



