222 MEMOIRS ON THE COLEOPTERA 



Posterior angles of the prothorax obliquely sinuate, dentate at base as 

 well as before the base; pronotum of the male not differing much 

 from the female and without sharply defined smooth areas 3 



3 Inner margin of the met-episterna broadly sinuate throughout, 

 mandibles much elongated in the male but less densely pilose within 

 than in Mallodon Nothopleurus 



Inner margin of the met-episterna straight, the latter subparallel, with 

 the sides not at all sinuate 4 



4 Mandibles very elongate in the male, the internal fringe of hairs less 

 dense than in Mallodon, the maxillary palpi with a few stiff hairs; 

 prosternum carinate except anteriorly: Stenodontes 



Mandibles not so elongate or widely separated in the male, irregular, 

 tridentate and densely pilose within, the two submedian teeth 

 united; maxillary palpi with regular marginal fringes of short hairs; 

 prosternum not carinate *Aplagiognathus 



5 Prothorax at the sides and base nearly as in Mallodon, rounded at the 

 base and with only an ante-basal tooth; tarsi widely dilated; pro- 

 sternum not carinate Paramallus 



These genera, with the exception of Mallodon, are exclusively 

 American and some of them, such as Stenodontes, rather restricted 

 in habitat; they differ a good deal among themselves in general 

 habitus, Paramallus, for example, with its very convex body and 

 short pendant mandibles, being very different in appearance from 

 Mallodon, with which LeConte united our representative species. 



Mallodon Serv. 



Besides the common dasystoma Say, my cabinet includes the 

 two following species, represented at present only by the female: 



Mallodon debile n. sp. Female narrow, moderately convex, shining, 

 castaneous; head very coarsely, deeply, irregularly foveato-punctate, 

 with a fine striiform median line; antenna? piceo-castaneous, short, the 

 first six joints extending barely to the base of the prothorax, the third 

 joint twice as long as wide, the fifth but little longer; prothorax as in 

 dasystoma but shorter and with the sides converging much more from 

 base to apex, differing also in having the inner lateral ridge wholly obso- 

 lete; elytra four-fifths longer than wide, more convex than in dasystoma 

 and differing in being ogivally narrowed behind from a little behind the 

 middle, the combined apices very narrowly parabolic, finely, sparsely 

 and obsoletely punctulate. Length 28.0 mm. ; width 9.3 mm. Alabama, 



Differs from the female of dasystoma in its narrower and more 

 convex form, shorter antennae, with shorter and less basally nar- 

 rowed first joint, and in the form of the posterior parts of the elytra, 

 but most decisively in the form of the fifth ventral segment, which 

 in that species, is between three and four times as wide as long. 



