402 



NATURAL HISTORY OF ARTHROPODS. 



Fio. 505. — Omus 



ani. 



the elytra are widely inflexed, the prothorax scarcely margined, and the terminal 

 joint of the maxillary palpi shorter than the third joint. A. cylindriformis, the only 

 species, is found in Kansas, Neiv Mexico, and Arizona. It is the largest 

 species of this family found in the United States, and is brownish-black 

 in color. Its habits are nocturnal. In Omus the elytra are narrowly 

 inflexed, the prothorax distinctly margined, and the last two joints of 

 the maxillary palpi subequal. The nine described species are all from 

 the Pacific slope, of North America, and are nocturnal. 



In Tetracha, the only representative of the Megacephalini found 

 in the United States, the eyes are large and prominent, the posterior 

 coxsB contiguous, and the third joint of the maxillary palpi longer 

 than the fourth. T. virginica is dark metallic green above, with light 

 brown legs and antennae. Its length is about 0.75 of an inch. It 

 is found in the southern Atlantic states concealed under logs 

 and bark by day, for its habits are crepuscular. T. Carolina, 

 which has a yellow spot near the apex of each elytron, and is 

 about 0.6 of an inch long, is widely distributed over America, from 

 the middle United States to Chili and Peru. 



The Cicindelini are represented by about sixty North American 

 species of Cicindela. In these insects, the third joint of the max- 

 illary palpi is shorter than the fourth. The five species of Cicin- 

 dela figured are all common in the northeastern United States. 

 Their size and figuration are well illustrated in the cuts. C. sex- 

 guttata is very bright metallic green, often with a bluish lustre, fig. soe.— Te^rocfta 

 and the yellow spots upon its elytra are subject to some variation. 

 This species, like the next, frequents sunny roads in the woods, where the orass is worn 

 down quite short. C. purpurea is purplish-bronze color, with the lateral margin of the 

 elytra metallic green, and the markings upon the elytra yellow. C. generosa is cop- 

 pery bronze color, with the yellow elytral markings extending as an outer margin 



Fig. 507. — Tiger beetles, a, Cicindela generosa ; b, C. tramquebanoa ; c, C. purpurea; d, C. 7iirtioollis; 



e, C. sex-guttata. 



around the elytra, and C. tranquebarica and C. hirticollis are of dark bronze color, 

 sometimes almost black, with yellow markings on the elytra. C. generosa, C. tran- 

 quebarica, and C. hirticollis frequent sandy river banks. In C. dorsalis, which swarms 

 along the south coast of Long Island, the elytra are nearly white, and the purplish 

 prothorax is clothed with white scale-like hairs. This coloration is evidently pro- 

 tective ; for these beetles are very difficult to see upon the white sand of the sea- 

 shore, and still more difficult to capture, as they fly, without the slightest hesitation, 

 directly out over the surf. 



GrEOKGE DniMOCK. 



