184 ACADEMY OF NATURAL SCIENCES 



PRIONUS Geoff. Fabr. Oliv. Latr. 

 1. P. DASYSTOMUS. — Eeddish-brown; head black; thorax 

 denticulate each side ; teeth small ; labrum and mandibles within 

 with ferruginous hair. 



Inhabits the lower part of the Missouri river. 

 Body reddish-brown, punctured : head black ; punctures pro- 

 found ; a longitudinal, impressed line : eyes black-brown ; a small 

 tubercle over the insertion of the antennae, and a larger, com- 

 pressed, emarginate one at the outer base of the mandibles : an- 

 tennae compressed, punctured, mutic, short ; labruin and mandi- 

 bles within with dense, rufous hair : palpi piceous : thorax with 

 crowded, irregular, minute, profound punctures ; an impunctured 

 large spot each side of the middle; a transverse one on the mid- 

 dle of the base, and one or two oblique, abbreviated lines each 

 side ; lateral edge dentated with from 5 to 14 small teeth ; elytra 

 mucrouate; punctures obsolete: beneath paler; region of the 

 mouth rugose with confluent punctures : postpectus with yellow- 

 ish hair : tarsi yellowish. 



Length one inch and three-tenths. [327] 



This species, in habit, approaches P. r^Iiiuh-icus and cilijjes, 



but is at once distinguished from both, besides other characters, 



by the very hairy appearance of the labrum, and of the inner 



side of the labrum [mandibles]. 



[Belongs to Mallodon. — Lec] 



2. P. EMAROiNATUS. — Castaneous, hairy ; thorax one-toothed; 

 antennae fourteen-jointed. 



Inhabits Arkansa. 



Body castaneous : head, thorax and breast covered with long 

 yellowish-ferruginous hair : antennae fourteen-jointed, glabrous, 

 perfoliate, imbricate ; the imbrications emarginate beneath ; man- 

 dibles black at tip : thorax but slightly margined, one-toothed on 

 the middle of the lateral edge : angles obtusely rounded : elytra 

 somewhat inequal, punctured : feet and venter subglabrous. 



Length nearly seven-tenths of an inch. 



Female glabrous; antennae simple. 



Length four-fifths of an inch. 



[Vol. III. 



