Sept.-Dec, i9i8.] VaN DyKK : REVIEW OF GeNUS SiLIS. 161 



dinner." While not looking for Hormops, I was overjoyed at meet- 

 ing it and its capture will long be remembered as one of the most 

 interesting episodes of my collecting days. 



A REVIEW OF THE SPECIES OF THE COLEOP- 

 TEROUS GENUS SILIS LATR. WHICH ARE 

 FOUND IN AMERICA NORTH OF MEXICO. 



By Edwin C. Van Dyke, 



Berkeley, Cal. 



In this paper are included under Silis, not only all of those spe- 

 cies which were listed as such by LeConte in his last revision,^ but 

 also those of Ditcmnus Lee, for as has been shown by Gorham, Pic, 

 Champion, and other recent workers, the members of the one grade 

 gradually into the other. As stated by Champion,- the latest to dis- 

 cuss the genus, Silis may be defined as having the " prothorax with 

 the lateral margins incised or constricted at or towards the base, and 

 sometimes (Ditemnus) deeply incised at about the middle also, the 

 margins more or less lobed, lamellate, or dentate, the lobes often im- 

 bricate, the tarsal claws uncle ft, and the seventh ventral segment 

 divided down the middle in J*."' In our fauna, two related genera, 

 Discodon Gorh. and Polcmins Lee, which have in common with it 

 the divided seventh ventral segment in the male, form with it the 

 group Silini. The genus presents many attractive features such as 

 the peculiar prothoracic armature in the males, the dichromatic and 

 polychromatic races, and the peculiarities of distribution. The arma- 

 ture is often grotesque in structure, is always of a distinctive type in 

 each species and so most useful in classification, and no doubt houses 

 certain of the special sense papillae. The female as a rule is without 

 any indication of this structure, having a prothorax with simple out- 

 lines. She is, therefore, hard to definitely identify unless found in 



1 " Synopsis of the Lampyridae of the United Stcites," by John L. LoConte, 

 M.D., Trans. Am. Ent. Soc, Vol. IX (1881), pp. 56 and 57. 



2 " Revision of the Mexican and Central American Telephorinse (Fam. 

 Telephoridae), with descriptions of new species," by George Charles Champion, 

 F.Z.S., Trans. Ent. Soc. London, Vol. 1915, p. 99. 



