270 E. T. CRESSON, JR. 



Dipterorum, amends the name to Dorylas. With these few 

 words of analysis and explanation I will let the matter drop 

 as irrevelent to the purpose of this paper. 



For the proper description of the species in this paper, 

 names are used which may be unfamiliar to many students, 

 and to some parts of the genitalia I have given arbitrary, or 

 provisional, names for convenience, as I have no time to go 

 into anatomy and terminology. All these names I will here 

 explain. 



The squama, in this family, are mere ciliate ridges, being 

 rudiments of a pair of membraneous scales situated above 

 the halteres and back of the root of the wings, perhaps more 

 often known as Tegulce, Calyptrce or Alula. The ventral 

 margins of the abdomen are the ventral portion of the dorsal 

 plates; the lateral angles of the segments I have designated 

 as the lateral portion of the apical margin just where the 

 dorsal plates turn down ; these angles are often pollenose, 

 being the dorsal attenuations of the pollen on the ventral 

 margins. The examination of the genital apparatus shows 

 a similarity in structure but great diversity in form. It is 

 here that much can be done in the study of this family. I 

 have not given these organs as much importance as they 

 probably should have ; but it appears to me that in some 

 species there is much variation, or, on the other hand, the 

 forms I have included under one may be distinct. 



The hypopygium of the male seems to be composed of five 

 separate, at least externally, chitenous sections or lobes, of 

 which, in some species of Pipunculus, only one, the terminal 

 lobe, is visible ; this is sometimes very irregularly developed, 

 being strongly compressed laterally, usually to the right of 

 the median line of the abdomen, in which case the hypopy- 

 gium is said to be assymetrical. This lobe is generally, but 

 not always, furnished, usually to the right of, or at its 

 apex, with an indentation or cleft, sometimes known as the 

 rima, and which in the genus Verrallia (Fig. 44) completely 

 divides this lobe dorso-ventrally into two separate parts, or is, 

 in a species of Pipunculus so widely developed as to occupy 

 nearly the entire lobe, or at other times is only indicated by 



