20 Mr. G. C. Champion's Revision of the Mexican 



Group SiLiNi. 



The genera here placed under the Silini agree in the 

 following characters : Seventh ventral segment of cJ com- 

 pletely divided down the middle, the eighth polished and 

 covered by the seventh ; genital armature symmetric, con- 

 sisting (at least in Discodon and Polemius) of several pairs of 

 hooks or spines, which can be withdrawn within the internal 

 sac; last joint of maxillary palpi securiform or cultri- 

 form ; prothorax (except in a few species) notched at sides 

 in (^, and often to a less degree in $; elytra long. This 

 group is abundantly represented throughout Tropical 

 America, and includes the following genera — Discodon, 

 Polemius, Silis, Parasilis, Malthaster, etc. 



Discodon. 



Discodon, Gorham, Biol. Centr.-Am., Coleopt. iii, 2, pp. 78 

 (1881), 285 (1885) (part.); Schaeifer, Journ. N. York 

 Ent. Soc. xvi, p. 61 (1908). 



The principal characters given for Discodon are the cleft 

 external tarsal claws, the feebly notched sides of the pro- 

 thorax, and the bilobed or divided seventh ventral segment, 

 of the male. This definition applies to most of the species 

 included in the genus by Gorham, but, on examination, 

 six of them {serricorne, lugubre, difficile, pJiotinoides, 

 flaccidutn, and bivittatum) prove to have the corresponding 

 tarsal claws simply lobed at the base and undivided at the 

 tip, and one of them {serricorne) wants the prothoracic 

 notch. As Discodon (type, D. erosum, Gorh.) can only be 

 separated from Polemius, Lee. (type, Cantharis laticornis, 

 Say), by the cleft claw of one or more of the (^ tarsi, the six 

 species above mentioned must be transferred to Leconte's 

 genus. Numerous forms, too, placed by Gorham under 

 Silis, in his Supplement to the " Biologia," have one or 

 more of the (^ tarsal claws cleft, and they are here included 

 under Discodon; some of these insects are closely related 

 to D. tenue and D. cinereum, others, D. serrigerum and its 

 allies, all of which have broad, serrate, tapering antennae, 

 mimic Lycids. D. lampyroides, nor male, and luridum, 

 on the other hand, have the general facies of Lampyrids. 

 Schaei^er has recently described four species of Discodon 

 from the Southern United States,* and Polemius planicollis, 



* D. telephoroides must be a Polemius. 



