OF NAtURAL HISTORY. 637 



[Belongs to Silis, and is the female of the species afterwards 

 described by me as S. longicomis. — Leg.] 



4. C. BIDENTATA nob. Journ. A. N. S., may prove to be a 

 Silis Meg., but as my specimen is imperfect, I cannot determine. 



MALTHINUS. [160] 



M. MARGiNiLis nob. (Molorchus) Journ. A. N. S. 1824, read to 

 the Society the preceding year. Malthinus latipennis ? Germar, 

 Spec. Novie, p. 72, 1824. 



DASYTES Payk. Fabr. 

 To this genus, as I now understand it, belong several species, 

 which I published under the genus MalacMus ; such as termi- 

 nalis nob., &c. 



TILLUS Fab., 



T. ? TERMINATUS. — Black; terminal joint of the antennae as 

 long as the head and thorax. 



Inhabits United States. 



Body black, densely punctured and with numerous cinereous 

 hairs : eyes reniform, emargination very profound : antennae, 

 radical joint suboval ; second joint globular ; third, fourth, fifth 

 and sixth, very short, transverse, approximated ; seventh, eighth 

 and ninth, rather larger, serrate ; terminal one greatly elongated, 

 longer than the head and thorax, and about three times as long 

 as all the preceding joints conjunctly, much compressed, linear, 

 with dense minute black hairs, tip. and base rounded : labrum 

 rounded at tip : mandibles bifid at tip : thorax cylindrical, hardly 

 narrowed at base, margin rufous : tarsi distinctly five articulate ; 

 first joint longer than the second ; penultimate one bilobate : 

 nails dentated : abdomen sanguineous ; terminal segment black. 



Length rather more than one-fourth of an inch. 



I obtained two specimens of this curious insect, at the [ 161 ] 

 cantonment of Major Long's party near Council Bluff on the 

 Missouri river. It occurs also in Indiana and Pennsylvania. 



By the form of the tarsi, palpi and thorax, it approaches the 

 present genus ; but the extraordinary conformation of the an- 

 tennae seems to require a separation from the other species, at 

 least in a distinct subgenus. 

 1835.] 



