1354.] 



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Descriptio?is of the species of Trox and Omorgus inhabiting the United States. 



By John L. LeConte, M.D. 



Trox Fabr. 

 A. Thorax incequalis prrzcipne bicostatus. 



1. T. S o n or ae , oblongus niger, thorace latitudine fere triplo breviore, ir- 

 regulariter grosse punetato, inaequali, disco elevato bicostato, lateribus late 

 rotundatis, elytris costis quatuor suturaque elevatis haud interruptis, sptis sor- 

 didis brevissimis tesselatis, interstitiismuricato-punctatis cicatricosis, tuberculis 

 parvis uniseriatis notatis. Long. *38. 



One specimen, Tucson, Sonora. This species is very similar to the next, but 

 the sides of the thorax are less rounded, being almost straight near the base ; 

 the furrows of the elytra are distinctly tuberculate, and the general form of the 

 body is narrower. Nevertheless, a larger series of specimens may prove these 

 differences to be of no value. 



2. T. al t e r n a n s , oblongus, niger, thorace irregulariter grosse punctato, 

 latitudine fere triplo breviore, lateribus modice rotundatis, elytris costis quatuor 

 suturaque elevatis haud interruptis, setis-sordidis brevissimis tessellatis, inter- 

 stitiis muricato-punctatis, transversim cicatricosis, tribus internis simplicibus, 

 quarto costula intermedia notato. Long. -37. 



Kansas Territory and New Mexico. The head is scarcely tuberculate, 

 densely punctured with the clypeus rounded, not margined ; thorax two and a 

 half times wider than long, moderately rounded on the sides, ciliate with yel- 

 low bristles, irregularly and coarsely punctured, unequal, with the middle of the 

 disc strongly elevated and bicostate, the intermediate furrow being divided by 

 a slight transverse elevation about the middle. Elytra oval, truncate at base, 

 finely serrate on the sides, with four elevated uninterrupted costae, which are 

 tessellated with short yellowish bristles, and alternate shining spots ; suture 

 elevated ; the three inner spaces are broadly concave, with irregular transverse 

 elevations, and sparingly marked with small muricate punctures, arranged nearly 

 in four series, but not so closely placed as to render the arrangement obvious ; 

 in some directions the transverse elevations seem to indicate a row of tubercles, 

 but this is also very indistinct ; the fourth space is marked with an indis- 

 tinct interrupted costa, forming a row of tubercles ; at the tip of the elytra 

 all these irregularities fade away, and the ordinary arrangement of striae 

 may be traced. The capillary striae seen in many species are here en- 

 tirely wanting:, except in the subsutural space where they may be faintly 

 discovered. The anterior femora, as in most species, are strongly dilated 

 and crenulate inferiorly; the anterior tibiae of one specimen from Kansas 

 are without teeth; in the New Mexican specimen, besides the ordinary 

 square terminal tooth, there are two small ones at the middle, and some fine 

 serrations towards the base. 



A specimen from Kansas, of smaller size (.35) has the costae of the elytra 

 less elevated and the interstices less corrugated, so as to present, besides the 

 very small muricated punctures, two rows of large subquadrate punctures, 

 nearly as in T. p o r c a t u s , from which, however, it is abundantly distinguished 

 by the differences in the form and sculpture of the thorax, and by the absence 

 of the capillary striae of the elytra. 



3. T. s o r d i du s, niger, thorace flavo-ciliato, brevissime setoso. inaequali 

 irregulariter grosse punctato, lateribus late rotundatis, medio modice elevato 

 bicostato, elytris costis quatuor interruptis, suturaque elevatis brevissime setosis, 

 postice indistinctis, interstitiis inequalibus bistriatis, tuberculisque parvis uni- 

 seriatis. Long. *3. 



Georgia, New York, Kansas. Smaller than the preceding, with the sides of 

 the thorax less rounded and the disc less elevated. The second and third costae 

 of the elytra are more interrupted than the first and fourth, and all are indis- 

 tinct posteriorly ; when the inequalities of the elytra are less marked, the 



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