86 COLEOPTERA OP NORTH AMERICA. 



Rhizophagini of Nitidulidae, and, like them, the males have a 

 small terminal dorsal segment; the form of the anterior coxae at 

 once separates them from all Nitidulidas. 

 The genera are : — 



Antennae with the ninth and tenth joints enlarged ; 

 Ninth joint of the antennae as wide as the tenth; 



Sides of the head slightly dilated before the eyes ; surface finely punc- 

 tured and pubescent. Phyconomus. 

 Sides of the head not dilated ; body glabrous, coarsely punctured ; ely- 

 tra punctured in striae. Nomophlcsus. 

 Ninth joint of the antennae not as wide as the tenth ; body coarsely punc- 

 tured ; elytra punctured and pubescent in striae. Hesperob^kus. 

 Antennae with the ninth joint scarcely larger than the eighth ; 



Head short ; body sparsely, coarsely punctured ; elytra punctured an J 



pubescent in striae. Bactridium. 



Head long ; body irregularly, densely punctured. Monotoma. 



The type of Phyconomus is Monotoma marinum Lee. ;* it is 

 found in California, under decaying kelp on the sea-shore. 



Nomophloeus is founded on N. pallipennis Lee, a small red- 

 dish-brown insect, 11 inch long, found in Pennsylvania. The 

 elytra are pale, with the suture and tip dusky. The head and 

 thorax are sparsely punctured ; the latter is quadrate, scarcely 

 serrate on the sides, with a broad smooth dorsal vitta, limited 

 behind by a curved impression. 



Hesperobrenus contains Monotoma rufipenne Lec.f from Cali- 

 fornia, and a nondescript from the Atlantic States. Ehizophagus 

 capito Fairemaire, from Honolulu, also belongs to it. 



Bactridium comprises Rhizophagus nanus Er. from the Atlan- 

 tic States, and Monotoma striatum Lee. \ from the Colorado 

 Desert. 



Fam. xvil— trogositidae. 



Meritum transverse, subquadrate; ligula small, corneous. 



Maxillas with two lobes, the inner one sometimes very 

 small; palpi short, 4-jointed. 



Eyes usually reniform (divided in some foreign genera). 



Antennre inserted under the frontal margin, 11-jointed, 

 rarely 10-jointed (in some foreign genera); the last three 

 joints widened, forming a loose club, of varied form. 



* Proc. Acad. Nat. Sciences, Philad., 1858, p. 64. 

 t Ibid., p. 64. % Ibid., p. 65. 



