2 PROCEEDINGS OF THE NATIONAL. MUSEUM. vol.64. 



that they possessed excellent specific characters. After separating 

 the various species of males by this means, it was found that external 

 structural characters could be correlated with the specific characters 

 found in the genitalia, and that keys based on external characters 

 alone could be made. 



Edward Saunders (1884) was the first to point out the taxonomic 

 value of the male genitalia in the aculeate Hymenoptera, and he 

 figured them for a number of families. Kadoszkowski (1885) figured 

 and described these structures for a lar^e number of Mutillidae with 

 the intention of revising the classification of the family. However, 

 from that time until recently, the male genitalia of the Mutillidae 

 do not seem to have been seriously considered as possessing good 

 specific or generic characters, although in several cases they have 

 been figured for a number of species. 



The morphology and homologies of the male genitalia of the 

 Hj^menoptera have been discussed by Peytoureau (1895), Bordas 

 (1895), Zander (1900), and Crampton (1919, 1920). Dufour (1834), 

 Saunders (1884), and Kadoszkowski (1885) describe their structure 

 in the Mutillidae in considerable detail. The nomenclature of the 

 parts (pi. 1, fig. 1) used in this paper is that given by Bradley (1917). 

 The parts which have proved most useful for specific characters are 

 the squama, sagitta, volsella, and ramus. In the various species these 

 parts exhibit a great variety of form and vestiture. In the genus 

 Pseudomethoca Ashmead, at least, the uncus and the cardo do not 

 appear to be important as far as specific characters are concerned. 



The external structural characters which have been found useful 

 in separating either the females or the males are as follows: The 

 dentate condition of the genae of the females together with the 

 character of the longitudinal carina of the genae ; the distance be- 

 tween the antennae at their base; the character of the frontal 

 tubercles at the base of the antennae; the character of the cephalic 

 margin of the propleura and the humeral angles of the pronotum; 

 the relative width of the head and thorax; the shape of the thorax; 

 the sculpture of the pygidium of the female ; the form and sculpture 

 of the tegulae of the males; and the sculpture and vestiture of 

 other sclerites of the head, thorax, and abdomen. 



The average worker will not find it necessary to examine the male 

 genitalia in order to identify specimens, but an account of the 

 technique used in removing these structures without injury to the 

 specimen may prove of value to those who wish to examine them. 

 The instrument used for dissection is a No. 00 white pin. The 

 tip of this is bent to form a very minute hook, and the head of the 

 pin is fastened into a small piece of cork, which serves as a handle. 

 The specimen is first relaxed, then holding it in one hand, the probe 



