1919.] NATURAL SCIENCES OF PHILADELPHIA. 55 



A STUDY OF THE ORTHOPTEROUS GENUS MERMIRIA STAL 



BY JAMES A. G. REHN 



For a number of years we have found that any attempt to make 

 determinations in this genus from the basis of the last revisionary 

 treatise published upon, it, that by Scudder in 1899, led us into 

 difficulties, some clearly evident, others more subtle and then 

 not possible of correction. In order to clear up the situation, 

 Mr. Morgan Hebard and the author, in the course of extensive 

 field work on the North American Orthoptera, have paid particular 

 attention to this genus, as a result of which a most extensive series 

 has been made accessible for study. 



Within the last five years or so we have received an added incen- 

 tive for making a comprehensive taxonomic, variational and dis- 

 tributional study of the genus Mermiria, in that we have had the 

 pleasure and profit of association with Dr. C. E. McClung, who 

 has made extensive studies on the chromosomes in this genus. 

 From his work he was able to point out certain evident differentia- 

 tions, which our studies show to be reflected in the external mor- 

 phological features, and it was his earnest desire that a good taxo- 

 nomic groundwork be laid for future work, cytological as well 

 as morphological. 



The author owes much to the encouragement and assistance 

 of Dr. McClung in the preparation of this paper, the assistance 

 being of a practical character, as the basic sorting of the whole 

 series studied was made by him in intervals between his official 

 duties, and the first draft of a key to the species was also drawn 

 by him. The cordial cooperation and valued suggestions given 

 by him have made easier some of the irksome portions of the 

 examination and analysis of the really large series on which this 

 paper is based. We are also indebted to our colleague, Mr. Hebard, 

 for numerous suggestions and kindly criticisms, as well as unre- 

 stricted use of his collection. 



MERMIRIA Stal 



1839. Opsomala Serville, Hist. Nat. Ins., Orth., p. .586. (Part.) 

 1870. Opoinola Thomas, Proc. Acad. Nat. Sci. Phila., 1870, p. 77. (Error 

 for Opsomala.) 



