1921] Wheeler: Some Social Beetles 51 



The Social Beetles. 

 a. coccidotrophus socialis schwarz and barber. 



After a careful taxonomic study of the beetles which I found 

 in the Tachigalia petioles, Messrs. Schwarz and Barber conclude 

 that they belong not only to perfectly distinct species but to 

 different genera of the family Silvanidse. While still at Kartabo 

 I convinced myself of their specific difference, but unfortunately 

 not till it was too late to make a detailed study of the differences 

 in their behavior. While the species described in Zoologica III, 

 No. 5 as Coccidotrophus socialis was so abundant that I obtained 

 nearly four hundred of its colonies, Eunausibms jvheeleri was so 

 scarce that I encountered it in less than a dozen petioles. For some 

 lime I took it to be merely a depauperate variety or aberration 

 of the Coccidotrophus and therefore gave it little attention. 

 Finally, when I had come to appreciate its distinct specific status, 

 my stay at the laboratory was drawing to a close and I could 

 secure only a few of its colonies. My account, therefore, relates 

 almost entirely to Coccidotrophus and my notes on Emiausibius 

 yield only a few rather summary remarks which may be most 

 conveniently relegated to a brief separate caption (p. 88). 



The Coccidotrophus (Plate III, fig. 2; Plate VI, figs. 1-5) 

 was taken only near Kartabo and only in the petioles of young 

 Tachigalias growing in the shade along the Puruni, Hacka and 

 Cuyuni trails, within a mile of the Tropical Laboratory. Although 

 the tree was not uncommon in the jungle behind H. M. Penal 

 Settlement and along the trails in the primeval forest near 

 Kalacoon and Baracara, I found no traces of the beetle in these 

 localities. It would seem, therefore, to be rather local. Its body 

 is flattened-cylindrical, long, slender and parallel-sided, with 

 short, stout legs, the femora, especially the fore pair, being con- 

 spicuously thickened. It varies in size from 3.5 to 4.5 mm. and 

 when fully mature is deep castaneous brown to almost black, with 

 more reddish appendages. Specimens recently emerged from the 

 pupa, however, are pale reddish testaceous, with more yellowish 

 elytra. The surface of the body is shining and glabrous, the 

 head and thorax punctate, the elytra punctate-striate. The head 

 bears a singular and significant resemblance to that of certain 

 small ants of the genus Cryptocerus. The antennae are short, 



