1856.] 19 



Resembles L. affinis, but is only one third the size; the impressions of the 

 elytra are also more irregularly distributed, and their sides are more rounded. 



6. L. 1 o n g i r , magis elongatus, thorace iuEequali, in latera fortius impress 

 eljtris humeris paulo productis. Long. '23. 



Narrower than any of the others : thorax one third longer than wide, very 

 gradually narrowed at base and tip, with the four dorsal impressions, and the 

 lateral ones well marked. Elytra only moderately emarginate at base, with the 

 humeri only slightly produced, and somewhat acute. 



7. L. morbiilosus, thorace iniequali, in latera minus profunde impresso, 

 ad apicem transversim paulo elevato, elytris humeris parum productis. Long. 

 25. -3. 



Resembles in form and characters L. affinis and L. erosus; it is inter- 

 mediate in size, but the humeral angles are less prolonged, being, in fact, but 

 slightly produced, and subacute. 



These species occur under dried buffalo excrement in the desert region along 

 the valleys of the Platte and Arkansas river : and are sometimes very abundant. 



Notice of three genera of Scarab^id^ found in the United^ States. 

 By John L. Le Conte, M. D 



On account of the great resemblance in appearance betwet,s species of different 

 genera among several of the tribes of Scarabteidae, much confusion has resulted 

 from the effort to place our species properly. This has perhaps been particu- 

 larly the case with our smaller Dynastidae. Eight species were placed by me in 

 the genus Bothynus, and the species known to Burmeister were placed by that 

 author in Podalgus and Heteronychus. A more careful examination convinced 

 him that the reference to the former of these two genera was incorrect, and 

 peculiarities in the stridulating organs required the construction of a new genus, 

 Ligyrus Burm. (Lamell. 3,542.) Although Heteronychus relict us is not 

 mentioned, it also belongs to this genus, which comprises all the species from 

 the United States known Ao Burmeister, except his Podalgus obesus (Bothynus 

 castaneus Mels.) 



The genus Ligyrus possesses a small elliptical plate of stridulating surface on 

 the inner surface of the elytra, near the outer and posterior margin ; the mandi- 

 bles are strongly dentate externally, and the outer lobe of the rnaxillaB are toothed 

 at the tip. 



In the third volume of Prof. Lacordaire's admirable work on the genera of 

 Coleoptera, these genera are carefully divided into groups, with the characters sub- 

 ordinated ; and in one of the valuable notes he indicates the existence of a genus 

 not recognized by Burmeister, and distinguished by having no organs of stridu- 

 lation. No name was suggested, as the scope of Lacordaire's book permitted the 

 introduction of no new materials ; but, as I find myself under the necessity of 

 referring to the species in some catalogues now preparing for publication, I have 

 been obliged again to review those referred by me to Bothynus, and now present 

 the results, with the addition of two other remarkable genera. 



LiGYR0s Burm. 



As the inner surface of the elytra cannot always be conveniently examined, 

 the following characters may be used to recognize the species of this genus. 

 The mandibles are strongly toothed externally; the clypeus is only narrowly 

 margined, furnished usually with two small upright teeth at the apex ; the front 

 is always transversely carinated, but the carina does not reach the sides of the 

 head. The species may be divided into two groups, and the first may again be 

 subdivided according as the clypeus has one or two apical teeth. 



