NORTH AMERICAN COLEOPTERA. 179 



The oblique sinuatiou of the base of the thorax altliough fairly 

 well marked in the majority of the species is very variable, and 

 in many of the species of the second series not at all evident. 

 The extent of the expansion of the lateral margins of both thorax 

 and elytra is purely a specific matter, and will be refei'red to in the 

 descriptions. 



The epipleuriE show two fairly distinct forms. In those species 

 which have no expansion of the margin of the elytra, the epipleurse 

 are always very narrow at apical half, while in those with explanate 

 elytra the epipleuraj are broad until very near the apex. 



The sexual characters (if they have not escaped observation) have 

 never been referred to in print. The first joint of the anterior tarsus 

 is always more broadly dilated in the male ; the last ventral segment 

 has on each side a deep sinuation, the space between forming a 

 prominent oval lobe which has a finely impressed line at middle. 

 The last ventral of the female is entirely simple. Among the dif- 

 ferent males no part in analysis can be taken from the sexual differ- 

 ences as the variation is too slight. 



In one species {tenuilineata) it will be observed that the male is 

 shorter, the thorax scarcely wider at base than at middle, while in 

 the female the form of thorax is that usual in the genus. In miniata 

 also the males are shorter and more convex than the females. As 

 far as my observation goes the females are fully four times as numer- 

 ous as the males. 



As (Edionychis is so well known and abundantly repi-esented bv 

 species, it will be used as the centre of comparison for allied genera. 

 Attention is directed, however, to the fact that about the only char- 

 acter separating Physodactyla is in the present genus purely sexual, 

 that is, all male CEdionychls would be Physodactyla. 



The species with a single exception belong to the Atlantic region, 

 several reaching Arizona ; violascens is the only one at present known 

 from the Pacific slope. 



Based on the notes always given it is proposed to divide our species 

 into two .series in the following manner: 



.\nteniiEe stout, scarcely as loug as half the body: species larger and convex; 

 front oblique, interocular impression never very distinct, usually obliter 

 ated by punctures : thorax rarely widely margined ; elytra never explanate 



Series A. 



Antennie .slender, as long as, or longer than half the body; species small, much 

 depressed, front vertical, a deep, transverse, interocular depression : elytra 

 usually explanate Skkie.s B. 



