154 PROC. ENT. SOC. WASH., VOL. 20, NO. 7, OCT., 1918 



Good results have been obtained by mercuric chloride fixatives and 

 iron-hematoxylin stain. 



The fact to which attention is specially called in the present 

 communication is that the muscular coat of the ventriculus of 

 the honey bee is comprised of three layers instead of two, the 

 inner layer having been overlooked in the past. The writer is 

 indebted to Prof. W. A. Riley who has examined preparations 

 submitted to him and verified this observation. Naturally it will 

 be of interest to learn whether this third layer is present also in 

 the musculature of the ventriculus of other insects. 



TWO NEW SPECIES OF THE BLATTID GENUS ARENIVAGA 



(ORTH.). 



BY A. N. CAUDELL, 



Bureau of Entomology, United States Department of \ Agriculture, 



Washington, D. C. 



While making a critical study of the concealed genital organs 

 of the males of the material of the genus Arenivaga in the collec- 

 tion of the National Museum I detected five specimens from 

 Arizona which pcssess characters proving them to be very surely 

 distinct from apacha, the species with which they have been 

 hitherto confused. This species is described below as Arenivaga 

 genitalis n. sp. The studies which brought about the detection 

 of this interesting form were undertaken for the purpose of deter- 

 mining the identity of some specimens belonging to this genus 

 taken in Florida. The habitat of these Florida specimens lead 

 me to expect they would prove to be undescribed and an examina- 

 tion of their structure proved this to be the case. They are there- 

 fore herein characterized as a new species under the specific name 

 floridensis. 



The concealed genital organs of the species of Arenivaga are 

 easily brought into view by laying a fresh or relaxed specimen back 

 downward on a piece of cork and with a sharp scalpel separating 

 the subgenital plate for most its width from the preceding seg- 

 ment and laying it over to one side, holding it there till dry by a 

 pin stuck into the cork. The sinistral plate bearing the genital 

 hook should be partially raised and held back by a pin until dry. 



Arenivaga genitalis n. sp. 



Male. Closely allied to and hitherto confused with a/xii-liu Sauss., 

 from which species however it is easily distinguishable by the structure of 

 the concealed genital organs. The subgenital plate is here, as in allied 



