JOUKNAX. OP ENTOMOLOGY AND ZOOLOGY 161 



Genus Tomocenis Nicolet 



This genus seems So distinct from the other members of the 

 family Entomobryidae tliat some good authorities recognize a 

 family Tomoceridas. 



The eyes are twelve, six on each side of the head. The 

 antennae are long but do not exceed the body in any of my 

 species. The third and fourth segments of the antennae are 

 subdivided in short rings. The claws are armed and the teeth 

 simple. The tenaculum does not vary greatly, the base bears 

 anterior setae which differ somewhat. Each dentes is divided 

 by two transverse sutures into three regions and there are 

 spines on the middle and proximal regions. These spines 

 furnish good specific characters. The form of the mucrone is 

 distinctive of Tomocerus. Each bears, on the closed side, two 

 large proximal teeth, an apical tooth and a series of small 

 intermediate teeth. 



I have a large number of specimens of this genus but they 

 vary so from those described by Folsom (1913) that I am not 

 sure that I have more than two species. Folsom uses the dental 

 spines as one of the principal characters for distinguishing the 

 species. But among my specimens I am unable to find even 

 two that have the number and arrangement of the spines the 

 same. Therefore I cannot use them entirely in classification. 



Key to the Genus Tomocerus 

 A. Intermediate dental spines unequal, with a large spine 

 near the middle of the series ; one large distal spine. 

 B. Teeth of superior claw, four to seven. 



C. Dental spines simple. vulgaris 



BB. Teeth of superior claw, two. bidentatus 



Tomocerus vulgaris Tullberg 

 (Plate IV, Fig. 1) 

 Macrotoma vulgaris Tullberg, 1871 ; 1872. Uzel, 1890. 

 Tomocerus plumbeus Packard, 1873. 



Tomocerus vulgaris Tullberg, 1876. Renter, 1891; 1895. Brook, 

 1883. Dalla Tovre, 1888. Schott, 1894. Schaffer, 1896, 

 1900a; 1900b. Poppe and Schaffer, 1897. Scherbakov, 1898. 



