NORTH AMERICAN COLEOPTERA. 85 



A study of the species of CRYPTOBIUM of Nortli America. 



BY GEORGE H. HORN, M. D. 



The following study was begun with the intention of presenting the 

 observations regarding the variability of the males in their secondary 

 sexual characters, with the expectation that those fortunate enough to 

 possess large series would be enabled to re-arrange their material. Fear- 

 ing that the hints given might result in greater confusion than benefit 

 without applying them directly to the species, it has been thought a ad- 

 visable to extend the work making the study complete. 



Fortunately the typical material described by Dr. LeConte has been 

 before me at the time of the preparation of the work and this, with my 

 own more ample material, supplemented by that of Mr. H. Ulke, leaves 

 nothing to be desired in the study of the more difficult forms. 



It is to be regretted that the use of the table in series A pre-supposes 

 the possession of the two sexes. This is, however, unavoidable, but the 

 difficulty is not entirely insurmountable. 



Having acquired a large number of specimens of Cryptobium from 

 Texas and Arizona I noticed some sexual peculiarities which seem to 

 have escaped observation in species from other regions. That variations 

 similar to those about to be described do occur is rendered probable from 

 a few words by Dr. Sharp regarding the modification of the lobe of the 

 fourth ventral segment (Trans. Ent. Soc. London, 1876, p. 210) in the 

 Amazon species. 



As far as the species in our fauna are concerned it may be stated that 

 under all circumstances it is the males that have a plica or fovea on both 

 the third* and fourth ventral segments. The females have at most a 

 plica or fovea on the third segment, but never on the fourth, and in by 

 far the large majority of species the ventral segments in the female are 

 absolutely simple. 



There is no dilatation of the anterior tarsi of the male, and the two 

 sexes here precisely agree. 



* It must be borne in mind that the^first ventral is concealed under the coxae, 

 and the true second is the first visible segment. This method of numbering the 

 segments will prevail in the following pages. 



