64 COLEOPTERA OF NORTH AMERICA. 



labrum is usually margined with membrane, and usually, though 

 not always, bilobed. 



This sub-tribe is very closely related to the preceding tribe, 

 but the difference in the position of the antenna? will enable the 

 student to avoid confounding them together. 



The tarsi are 5-jointed, the middle coxa? contiguous, the hind 

 tarsi not dilated, and the maxillary palpi not dilated, in all of 

 our genera. 



Antennae geniculate, the first joint elongated. Acylophortjs. 



Antennae geniculate, first joint moderate ; anterior tarsi narrow. 



Eueypokus. 

 Antennae straight, first joint moderate ; anterior tarsi dilated ; 



Prothoracic spiracles uncovered ; palpi subulate. Hetekothops. 



Prothoracic spiracles covered, palpi filiform. Quedius. 



Sub- Tribe 2.— Stapliylinini (genuini). 



The antennae are inserted on the anterior margin of the front, 

 inside of the base of the mandibles, but distant from each other. 

 The thorax is more or less convex, frequently densely punctured, 

 with the lateral margin double ; the prothoracic spiracles are 

 always visible and uncovered ; the labrum is always bilobed ; the 

 antenna? are never geniculate. The suture is imbricate only in 

 Thinopinus. 



The species live on decomposing animal and vegetable sub- 

 stances, or on excrements; rarely (Thinopinus) on the shores of 

 the ocean, below high-water mark. Some of them are the largest 

 of the family. 



The genus Staphylinus, as set forth by Erichson, has been dis- 

 membered by later authors, to form several of the genera below 

 mentioned. 



A. Maxillary palpi with the fourth joint shorter than the third ; 



Thorax smooth, narrowed at the base ; 



Middle coxae contiguous, suture imbricated, wings none. 



Thinopinus. 



Middle coxae distant, suture straight. Ckeophihts. 



Thorax punctured, pubescent, narrowed at the base. Listotkophus. 



B. Maxillary palpi with the fourth joint equal to or longer than the third ; 



Marginal lines of the thorax separate, wings none. Hadkotes. 



Marginal lines of the thorax separate, wings distinct, last joint of la- 

 bial palpi truncate. Tkigonophorus. 



Marginal lines of the thorax united near the apex, body winged ; 

 Ligula emarginate ; 



