CONTENTS 
•^rhe North American Species of Gyrinus (Coleoptera). By 
H. C. Fall 269 
(Issued February 14, 1922.) 
Studies in Costa Rican Dermaptera and Orthoptera. Paper 
One. Two New Genera and Three New Species of 
Dermaptera. By James A. G. Rehn . . . 307 
(Issued March 3, 1922.) 
The Janeirensis Group of the Genus Euborellia, with the 
Description of a New Species (Dermaptera). By 
Morgan Hebard . . . . . . 319 
(Issued March 3, 1922.) 
Studies in American Ephydridae (Diptera). III. A Re- 
vision of the Species of Gymnopa and Allied Genera 
constituting the Subfamily Gymnopinae. By E. T. 
■ Cresson, .Jr 325 
(Issued March 15, 1922.) 
