204 [February, 



DESCRIPTION OF THREE NEW SPECIES OF TRIGONURUS. 

 BY D. SHARP, M.B. 



Dr. Leconte lias recently described a number of tbe more in- 

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

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

 found two new species of the important genus Trigonurus, — noteworthy 

 for the JSTew- 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 two 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, n. sp. 



Gastaneus, opacus, suh-parallelus ; thorace sub-quadrato, hasi hlsi- 

 nuato, angulis posteriorihus leviter acutis; elytris dense, fortiter, ruguloso- 

 et strinto-punctatis, apice recte truncatis ; ahdomine crehre fortiter 

 punctato. Long. corp. 5 mm. 



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

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

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

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

 on each side a rather 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 rugulose ; 

 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 structural characters this species closely approaches T. 

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

 structure of the prosternum ; 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. Mellyi ; 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. ri/gosus, 

 a trocliantin of the front coxa) is very distinctly visible. 



