196 CALIFORNIA ACADEMY OF SCIENCES. 



ate; the three outer joints in Sonoma are distinctly enlarged^ 

 forming a loose club. 



The transverse areas of sensitive surface near the apex 

 of the second dorsal segment are analogous to similar 

 transversely oval patches previously noticed by me a& 

 being very common in the Homalini of the Staphylinidae , 

 and they probably serve the same purpose in each group. 

 They have been noticed by Dr. Sharp in Sagola. Although 

 both the species of Sonoma before me have these sensi- 

 tive patches, I am not certain that their presence is con- 

 stant throughout the genus. 



OROPUS n. gen. (Euplectini.) 



Tarsi with two unequal claws, posterior coxse very closely approximate. 

 Maxillary palpi moderate in length, fourth joint rather elongate and spindle- 

 form, widest near the middle, bristling with minute seta at apex. Head 

 with two small occipital fovese, which are spongiose and connected by an 

 arcuate, impressed groove; antennae similar in the sexes; eyes well developed. 

 Prothorax with two lateral spongiose foveoe at base, connected by a deeply 

 impressed line, also with an impressed median canaliculation ; sides near the 

 base with a small, acute, reflexed tooth. Elytra with acute lateral margin; 

 each having four deep punctures at base, prolonged posteriorly as fine dis- 

 tinct strife. Abdomen with a short basal segment, hidden by the elytra 

 above, visible beneath, not extending beyond the coxae; second segment long, 

 more than twice as long as the third. Tarsi three-jointed; basal joint very 

 small, second very long. Abdomen strongly margined above. Body rather 

 robust and convex. 



This genus belongs to the Trichonyx group of the Eu- 

 plectini, but differs greatly from that genus in the position 

 of the posterior coxse, which are here very narrowly sepa- 

 rated, almost contiguous at base. In Trichonyx they are 

 quite distant, more than three times as distant as in the 

 present genus. Oropus belongs near Trogaster Sharp, and 

 differs from it in the form and position of the pronotal teeth. 

 In addition, the following characters distinctive of Trogas- 

 ter are not found in Oropus: — Antenu?e dissimilar in the 

 sexes; fourth joint of maxillary palpi rather short, widest 

 near the base; head with two small occipital foveae, which 



