AMERICAN COLEOPTERA. 81 



Synopsis of (he Ooiiora and Species of the Staphyliuide 

 tribe TACIIYTOKINI of the United States. 



BY GEORGE II. HORN, M. D. 



This tribe contains those genera and species in which the pro- 

 thoracic spiracle is not covered by the side pieces and the antennae 

 inserted under the side margin of the head, behind the base of the 

 mandibles and usually immediately in front of the eyes. 



There is at times a little trouble in deciding positively concerning 

 the insertion of the antennje, as in certain short-headed BoUtohius 

 the antennae become as it were pushed upwards and the line of de- 

 marcation between the present tribe and the group Quedii of the 

 next tribe becomes partially obliterated. 



As certain heretofore unused characters become prominent in the 

 succeeding pages, each portion of the body will be taken up by itself 

 so that special characters may be mentioned and explained, and the 

 differences and resemblances of genera shown before any tabular 

 arrangement is given. 



Head broadly oval in most genera, transverse in IJijiwcyptini^ 

 elongate to a variable degree in BoUtohius. The sides beneath the 

 eyes distinctly margined, Bolitobii, or without margin in the other 

 groups. 



Antennae eleven-jointed gradually broader to apex, ten-jointed in 

 Hypocypti and with the last three joints stouter or forming a club. 

 Filiform in most genera, slightly compressed in others or slender, loosely 

 articulated, ten-jointed and verticillate, Hahroceriis^ (fig. 30,* a). 



Maxillary palpi usually slender, four-jointed, the first very 

 small, second and third equal in length, the latter always stouter, 

 fourth variable, as follows ; 



slender, elongate, acute at tip, Ilabrocerus, (fig. 35, d); 



subulate, Mycetoporus, Conosoma, Tachyporus and the Hypocypti, 

 (fig. 35, c) ; 



conical, Bryoporus, (fig. 35, b); 



filiform, Tachinus, BoUtohius, Cilca, Physetojwrus and Erchomus^ 

 (fig. 35, a). 



ScuTELLUM visible, triangular; concealed in Hypocyptus and Ana- 

 cyptus. 



Elytra variable in length, prolonged below the sides of the body 



*The figure was copied from Erichson and has one joint too many for our 

 species. 



TRANS. AMER. ENT. SOC. TI. (12) JUNE, 1877. 



