18 [February, 



Note on the genus Lithodus Schonherr. 

 By JooN L. Le Conte, M. D. 



On examiaing a considerable number of specimens of this curious genus, pro- 

 cured by me several years ago, in the valley of the Platte River, it became evi- 

 dent at once that several species existed ; from the close resemblance in color, 

 form and sculpture, it seemed to be a matter of difficulty to separate them, and 

 I proposed to leave them until time and inclination would induce some entomo- 

 logist to labor upon a monograph of our native Curculionid<e ; such time being, 

 however, apparently remote, and desiring to make use of the names of these 

 objects in other investigations, I have thought it desirable to make them known. 



The species are all of a dull black color without lustre, and covered, when 

 alive, with a crust of dirty brown matter ; the surface is thinly clothed with very 

 short yellowish bristles, which proceed from punctures ; the punctures of the 

 head are small, and the front is deeply sulcate : the rostrum is shorter than the 

 head, flat, slightly narrowed in front, with the mandibles distinct. The thorax 

 is longer than wide, uneven, very coarsely punctured, rounded on the sides and 

 narrowed somewhat rapidly in front, (except in L. longior) ; the disc has four 

 %ague impressions, and sometimes a slight dorsal channel: the part near the apex 

 is transversely elevated, but more so in some species than in otjhers ; the sides 

 are transversely impressed near the apex. 



The elytra are convex, connate, declivous and somewhat pointed behind, emar- 

 ginate at base, with the humeral angles variously prolonged and embracing the 

 base of the thorax : they have rows of large irregular foveae, and the interstices 

 are alternately more elevated : between the foveae may be seen a few elevated 

 punctures. The legs are feeble, the tarsi are not dilated, and the pectoral ex- 

 cavation does not reach the anterior coxae. 



1. L. h u m eralis , thorace fortius inaequali, ad apicem fortiter ti-ansversim 

 elevato ; elytris humeris valde productis, ad thoracis tertiam partem extenden- 

 tibus, extrorsum curvatis. Long. -33. 



Germ, in Schonherr, Cure. 2, 420 ; 6, 2, 390. 

 Brachycerus humeralis Say, Journ. Acad. Nat. Sc. 5, 254. 

 Thecestermis humeralis Say, Cure. 8. 



The humeral angles are much longer than in any of the others, and very dis- 

 tinctly bent outwards. 



2. L. r e c t u s , thorace fortius inaequali, ad apicem fortiter transversim elevato ; 

 elytris humeris valde productis, ad thoracis quartam partem extendentibus por- 

 rectis. Long. -35. 



One specimen. The thorax is as strongly impressed, and as much elevated at 

 the base as in the preceding, but the humeral angles are less prolonged, and not 

 curved outwards. 



3. L. af finis, thorace minus inaequali, ad apicem modice transversim ele- 

 vato, in latera minus profunde impresso ; elytris humeris breviter recte productis. 

 Long. -35. 



Differs from the next by the less strongly impressed and less deeply punctured 

 thorax. 



4. L. r u d i s , thorace valde cribroso, inaequali, ad apicem magis transversim 

 elevato, in latera fortius impresso, elytris (saepe tomento variegatis) humeris 

 breviter recte productis. Long. -31. -35. 



The thorax is more strongly and densely punctured than in the others, and the 

 small elevations between the impressed foveae of the elytra are usually more 

 distinct. 



5. L. erosus, thorace minus inaequali ad apicem paulo transversim elevato, 

 Ln latera minus profunde impresso; elytris humeris breviter recte productis. 

 Lon^. '25, 



