AMERICAN COLEOPTERA. 219 



Synopsis of the SII.PHID.Ii: of the United States with 

 reference to the genera of other countries. 



BY GEORGE H. HORN, M. D. 



In its ori<j;in the present essay was intended to clear up some 

 doubtful points wliich appeared to exist in our series of Catops. 

 This required an examination of the genera into which it (or more 

 properly Choleva), had been divided, and necessitated a determination 

 of the question of the generic identity of the European and American 

 Adelops. The investigation gradually extended from one genus to 

 another until all the tribes were covered and almost unwillingly the 

 species were passed in review, and the paper has grown to a size far 

 beyond my first ideas. The door once open to foreign genera all have 

 been included in the study and will be found in their places in the 

 generic tables which follow, and in the event of any now unknown to 

 us being discovered, their recognition will be made easy without the 

 bibliographical research otherwise necessary. In dealing with genera 

 foreign to our fauna it has not seemed necessary to do more than put 

 them in their places, more would not be pertinent to the present essay. 

 Figures in outline of all known genera (with few exceptions) have 

 been given, nearly all of which have been drawn from nature. These 

 it is hoped will prove of further assistance. 



Ab might have been expected from an investigation of such a 

 character, the number of exceptional cases to the generally accepted 

 formula of the family has greatly increased. In order to call especial 

 attention to some of these the formula is here repeated, and the 

 exceptions indicated in as condensed a manner as possible. 



SILPIIID^. 



Mentum quadrate or slightly transverse, sometimes slightly emar- 

 ginate, frequently with a transverse piece between it and the ligula 

 which is prominent, either emarginate or bilobed ; mental suture 

 distinct. 



Maxilla with two lobes, inner sometimes with a terminal hook 

 {Silpha}, the outer rarely slender and filiform (^Cla7iihus). Palpi four- 

 jointed, the first joint always short, the others variable. 



Labrum usually visible, rarely almost entirely concealed ( Clamhini), 

 of variable form, sometimes entire^ usually emarginate or bilobed. 



