204 [February, 



DESCRIPTION OF THEEE NEW SPECIES OF TRIQONURUS. 

 BY D. SHARP, M.B. 



Dr. Leconte has recently described a number of the more in- 

 teresting of the new species of Goleoptera, discovered by the lamented 

 Gr. E.. Crotch, in California. Among these descriptions are to be 

 found two new species of the impoi'tant genus Trigonurus, — noteworthy 

 for the New-world Coleopterous fauna. I have for some years pos- 

 sessed three species of Trigonurus from California, and supposed, on 

 receiving Dr. Leconte's paper, that I should find tvro of them to be his 

 new species. Such, however, proves not to be the case ; for, after 

 examination of Leconte's descriptions, I am obliged to conclude that 

 I possess neither of his two species ; and I think it will be of interest, 

 therefore, to publish descriptions of the three species in my collection. 



Trigonurus rugosus, oi. sp. 



Castaneus, opacus, suh-parallelus ; tliorace sub-quadrato, hasi hisi- 

 nuato, anguUs p)Osteriorihus leviter acutis; elytris dense, fortiter, ruguloso- 

 et striato-punctatis, apice recte truncatis ; ahdomine crehre fort iter 

 punctato. Long. corp. 5 vwi. 



Head coarsely and closely punctured, with a deep transverse impression between 

 the insertion of the antennse. Thorax very nearly as long as broad, the sides a little 

 narrowed in front of the middle : it is densely and coarsely punctured, with a longi- 

 tudinal impression along the middle, whicli does not reach the base ; and it has also 

 on each side a ratluT large but ill-defined basal impression just within the angles. 

 The elytra are one and a half times the length of the thorax, but only slightly 

 broader than it ; they are very coarsely punctured, and the punctures are arranged 

 in rows, but they are very close together and the interstices are irregular or rugulosc; 

 the hind-body is rather closely and coarsely punctured. 



The dense coarse sculpture rendering the upper surface opaque^ 

 and the truncate apex of the elytra, make this species very easily dis- 

 tinguishable from all others of the genus. 



In its structiu'al characters this species closely approaches T. 

 Mellyi ; nevertheless, a difference exists between the two in the 

 structure of the presternum ; in T. rugosus, the posterior side piece of 

 the prosternum forms a true triangle ; it is a little further removed 

 from the front piece, the result of which is that the front coxae of 

 T. rugosus are rather more enclosed behind, but are more uncovered at 

 the sides than in T. MeJlyi ; should this structure be found similar in 

 the other A.merican species, it may be sufficient to warrant the 

 establishment of a separate genus. In both T. Mellyi and T. rugosus, 

 a trochantin of the front coxa) is very dietinctly visible. 



