10 



deepest longitudinally through the center; noticeably wider than the elytra 

 at their juncture, and rather wider than their greatest breadth; seen from 

 above the front margin appears truncate in the middle, then trends 

 obliquely forward to the angles which are prominent; sides straight for a 

 short distance, posterior angles strongly rounded; posterior margin much 

 extended in the middle with distinct sinuations toward the angles. The 

 front area deeply concave, surmounted with four well formed tubercles; 

 two occupying the center, bold and projecting over the concavity, two 

 others, one on either side of the central two situated near the anterior 

 margin of the thorax at its exterior angles. The area around the two 

 anterior tubercles very rugosely punctate ; and transversely across the disc 

 are large distinct punctures nowhere extending to the posterior margin. A 

 well defined margin, re flexed at the sides, surrounds the whole. Elytra: 

 very convex, obtusely rounded behind, having fourteen well defined and 

 regularly punctured striae, the interstices of which are flattened and indis- 

 tinctly wrinkled. The under side paler than the upper; dense fringes of 

 light chestnut hair line the reflexed portion of the thorax and elytra, while 

 the femora, tibia, and tarsal joints, as well as the lower side generally, are 

 well supplied with rather long chestnut hair. Length .48-. 52 inch. 



Female: Form and color as in male. Labrum pro- 

 jecting, rugose, covering the mandibles. Head : clypeal 

 margin raised; a feeble tubercle just in front of the 

 clypeal suture, immediately behind which is a central 

 transverse ridge, undivided, slightly higher in the 

 middle and slightly apiculate at either end. Anten- 

 nae less robust than in the male. Thorax : very convex, 

 shining; outline obtusely triangular; anterior margin 

 Female. seen from above, truncate in the center; angles pro- 



duced; sides rounded; posterior margin much produced to meet the scu- 

 tellum, sinuate toward the angles which are rounded; the front discal area 

 characterized by a bi-lobed transverse raised line, at either end of which, 

 outward and forward, is a well formed but ^ depressed tubercle; behind 

 which line the disc is dense with coarse corrugated punctures, which 

 become scattered and plain, nowhere reaching the posterior margin, but 

 taking a transverse course, barely reach the side margins, where they 

 become less distinct. - Elytra: much the same as in the male, but the 

 interstices of the fourteen punctate striae a trifle more wrinkled and much 

 more convex. Length, smaller than the male. 



Habitat: burrowing in the ground near the City of Sonora, Tuolumne 

 County, California; found also in Sacramento County. 



The name selected for this species is intended to be a small tribute of 

 honor to Dr. George H. Horn, the eminent Coleopterist, as a slight return 

 for many favors. 



STRIDULATING ORGANS. 



The sound of stridulating was first heard by Mr. Charles 

 Fuchs, of Alameda, who, having living specimens, made exam- 

 inations for the source of the sounds, and was rewarded by find- 

 ing the stridulating apparatus to be three bands situated one 

 each upon the fourth, fifth, and sixth dorsal segments, are well 

 developed, and when magnified show that these bands are set with bristles 

 in diagonal rows, the points of the bristles are bent downward, which, by 

 the quick contraction of the abdomen, these hooked bristles are brought 

 in repeated contact with the edge of the elytra arid thus causing the vibra- 

 tions known as stridulating. 



