I A REVIEW OF THE AMERICAN SPECIES OF 

 RUTELIN^E, DYNASTIN^: AND CETONIIN^. 



The primary divisions of the Scarabaeidae are not rigorously 

 definable and, in fact, after so long a period of geologic evolution, it 

 would be illogical to imagine any other condition than an inter- 

 blending of structural characters to such a degree as to render 

 delimitation of extended groups, in other than a general way, more 

 or less unsatisfactory. There is scarcely a structural feature 

 defining one group that may not appear in some other group. 

 This is in a measure true also of the more restricted subdivisions, 

 such as genera, except when monotypic. The discussion of these 

 points is made by Lacordaire so fully and so well, that it is not 

 necessary to go into the subject at the present time and in a work 

 designed more especially to differentiate and define the species of 

 a restricted fauna. 



Subfamily RUTELIN^. 



The essential structural peculiarities of this large and important 

 group of genera may be said to be the unequal tarsal claws, the 

 corneous ligula, which is rigidly fused with the mentum to form a 

 single large plate, the free labrum, the 9- or lo-jointed antennae, 

 invariably having a 3-jointed club, which is small or moderate in 

 length and, finally, the fact that the last three pairs of abdominal 

 spiracles rapidly diverge posteriorly, the last spiracle on (Plusiotis) 

 or just above (Anomalce) the suture between the last abdominal 

 plate and the propygidium. 



In the present paper I am disinclined to advance any changes in 

 the scheme of classification proposed by Lacordaire, except to 

 suggest that the singular membranous elytral margins might be 

 made a primary character, as the Geniatids appear to be more 

 closely allied to the Anomalids than they are to the true Rutelids, 

 and again because such an arrangement would shift the Dynastid- 

 like Parareoda, Byrsopolis and Polymcechus to the end of the 

 series, instead of separating these genera from the Dynastinae by 



T. L. Casey, Mem. Col. VI, Oct. 1915. 



