454 bulletin: museum of comparative zoology. 



in length with distinct, simple, impunctate striae. It is possible that 

 more than one species is included in the material but there seems to 

 be no sure means of separation with the specimens at hand. 



Ataenius restructus Wickham. 



Three specimens. No. 2,536-2,538 M. C. Z. (No. 2,471, 2,502, 

 11,298 S. H. Scudder Coll.). They agree Avith my type in size and 

 form and I think it best to assume their identity, although in some 

 lights the elytral striae seem to show signs of punctures. The speci- 

 men bearing Scudder's number 2,502 exhibits the hind tibiae very 

 nicely and from the slender structure of these parts and the lack of 

 distinct transverse ridges it seems wise to assign the species to Ataenius, 

 though I had first described it as an Aphodius. 



Aphodius Illiger. 



The removal of my A. restructus to the genus Ataenius leaves six 

 described species of Aphodius from the Florissant shales. Two new 

 ones are found in the present collection, both readily distinguishable 

 from those previously known. While mammal remains are practi- 

 cally unknown at Florissant, it is probable that the region adjacent to 

 the old lake was well populated with the numerous ungulate and other 

 types of mammals known to abound during the Tertiary times. It is 

 a matter of common knowledge that some of the species of recent co- 

 prophagous Scarabaeidae select the dung of one or more species of 

 mammal as food, in place of promiscuous feeding. Putting together 

 the known abundance of ungulates in the Tertiary period and the 

 selective habit of dung-eating beetles, it is reasonable to assume 

 that the great specific development in Aphodius at Florissant was 

 correlated with a plentiful supply of mammalian dung of different 

 kinds. It appears to me likely that a good many of these old Aphodii 

 became extinct along with the mammals that formed the sources of 

 their food supply. All of these Florissant fossil Aphodii belong to the 

 division of the genus with short scutellum — the same section that is 

 most abundant in North America today. None of them are espe- 

 cially peculiar in any way, though their specific characters are well 

 marked. Some of them must have occurred in considerable numbers 

 if we may judge by the frequency of their remains in the shales. 



