184 ACADEMY OF NATURAL SCIENCES 



PRIONUS Geoff. Fabr. Oliv. Latr. 



1. P. DASYSTOMUS. — Reddisli-brown 3 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 ; pimctures 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 ; labrum 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 

 mucronate; 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. cyllndricus and cilijies, 



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. EMARGINATUS. — Castaneous, hairy ; thorax one-toothed; 

 antennae four teen-jointed. 



Inhabits Arkansa. 



Body castaneous : head, thorax and breast covered with long 

 yellowish-ferruginous hair : antenuEe 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. 



