LeConte.] EHYN^CIIITID^. 3 



Family IT. RHY:N^CHITID^. 



Mentum small, subquadrate, supported upon a long narrow gular pedun- 

 cle ; ligula prominent, small, palpi short. 



Maxillae exposed, palpi short, rigid, as in Curculionida.', 4-jointed. 



Mandibles toothed on the outer and inner side ; capable of great lateral 

 extension ; in repose the outer apical tooth on each projects forwards, so 

 that two small acute teeth seem to project from the mouth. 



Antennae inserted at the sides of the beak, in position varying according 

 to the genus ; 11-jointed straight, first joint not elongated, and scarcely 

 stouter, 2 — 8 slender, 9 — 11 broader, forming a loose club, and covered with 

 sensitive surface. 



Head prominent, not deflexed, eyes rounded finely granulated ; beak 

 slender, varying somewhat in fonu according to the genus. 



Prothorax truncate before and behind, convex, prosternal sutures not 

 visible, coxal cavities rounded, somewhat transverse, with a distinct fissure 

 at the outer side margin : distant in Pterocolus, confluent in other genera.. 



Mesosternum flat, acute behind in all but Pterocolus, and with the side 

 pieces normal in form and diagonally divided ; in that genus they are trans^ 

 verse, prominent, apparently undivided, and ascend between the prothorax 

 and humeral angle of the elytra, suddenly declivous and excavated in front 

 for the protection of the legs ; coxal cavities appujoximate, except in Ptero- 

 colus. 



Metasternum rather long, with narrow side pieces ; shorter with wide 

 side pieces in Pterocolus. 



Elytra separately rounded behind, exposing the pygidium in some genera ; 

 conjointly rounded, and covering the pj^gidium in others, epipleui^se dis- 

 tinct ; submax'ginal fold on inner face short and straight. 



Abdomen with five free ventral segments, nearly equal, in length, sepa- 

 rated by straight sutures, intercoxal process acute except in Pterocolus ; 

 (^ without additional anal segment, pygidium in both sexes triangular, de- 

 flexed ; sides of segments not forming an acute edge, and not fitting into a 

 lateral groove of the elytra. 



Anterior coxse usually conical, contiguous, and prominent ; smaller, 

 rounded and separated in Pterocolus. 



Middle coxae similar to the front ones. 



Hind coxse transverse, reaching to the margin of the elytra, or nearly so. 



Legs slender, rather long, tibiae truncate at tip, with small terminal 

 spurs ; tarsi brush-like beneath, 4-jointed, thii*d joint broad deeply bilobed ; 

 claws bifid, or acutely toothed. 



Though nearly related to the preceding family, these species are readily 

 distinguished by the absence of labrum, and the peculiar form of mandible, 

 which recurs again only in De»moris, an Erirhine genus of Curculionidae. 



While in Rhinomaceridae a relationship to normal Coleoptera is seen in 

 the presence of a labrum, and better- development of maxillary palpi, a^ 



