NdRTIl AMERICAN OOLKOPTERA. 171 



siroiif^lv iiiargiiie(l. not serrate, a distinct carina witliin tlie ore:?t; elytra oblong, 

 humeri distinct, apices conjointlj- rounded in both sexes: surfac«» sliglitly shining, 

 moderately, densely, finely punctulate, clothed with rather <;(>arser hair, much of 

 which is long and erect, color rufo-testa<'eous. the apex Jiarrowly black, a transverse 

 band at middle, broadest at the suture and entire, and a small scutellar spot on 

 each side of the same color: body beneath rufo-teslaceous: abflomen sometimes 

 piceous. moderately, densely punctulate, and clothed with fine silken cinereous 

 pubescence. Length .14 — .IS inch: ?>.b — 4.5 mm. 



'J'he thoracic horn in this species attains greater dimensions than any 

 other in uiir fauna. In the female it is nearly as broad as long, and its 

 area when viewed from above nearly equal to half the body of the thorax. 

 The male has a narrower horn. The last ventral segment of the male is 

 truncate, and near the margin very feebly triangularly impressed. 



The most striking sexual character is observed in the anterior tibiae of 

 the male, which are provided with a strong triangular tooth at middle on 

 the inner side. There is no described species presenting such a character. 

 The color variations as far as observed are slight, and consist in a narrow- 

 ing of the middle band, and the extreme tip of the elytra pale. 



The type of the markings is similar to monodon. but in the present 

 species the band is exactly median. 



Occurs in Nevada, Arizona, Texas and Lower California. 



X. liiuiioilon Fab.— Moderately elongate, testaceous, clothed with coarse 

 pubescence, much of which is erect : elytra with scutellar spots, and a band slightly 

 post-median piceous: head sparsely punctate, front black; surface finely pubes- 

 cent, and with numerous erect hairs; thorax oval, slightly transverse, shining, 

 rather sparsely punctulate, horn moderate in length, margined, serrate at the sides, 

 crest variable, normally moderately elevated, slightly margined and serrate, 

 sometimes feebly elevated, scarceh' margined, the margin indicated by granular 

 elevations ; elytra oblong, humeri distinct, apices conjointly rounded in both sexes . 

 surface rather coarsely and moderately densely punctured, clothed with coarse, 

 rather long pubescence, with intermixed semi-erect longer hairs arranged in rows ; 

 body beneath rather densely punctulate. finely pubescent. Length .10 — .20 inch; 

 2.5—5 mm. 



The sexual differences are very feeble. The la.st ventral segment of 

 the male is more obtuse at apex, but I can find no trace of the impres- 

 sion usually observed in the other species. The horn is broader in the 

 female, but the difference is so slight that the sexe.s can hardly be sepa- 

 rated in this manner. 



Tile variations in the form of the horn are numerous, and independent 

 of sexual differences : these will be observed in the extent of the margin, 

 the mode and extent of the serration, and the form of the crest. In the 

 larger specimens the crest is well marked, distinctly margined and serrate ; 

 in smaller specimens the cre.st is .scarcely elevated, and the margin is 



