Biology of the Membracidae of the Cayuga Lake Ba.sin 355 



cussion in connection with the family. Whenever possible the terms 

 used in this study have been those defined in the very complete reports 

 on the lepidopterous genitalia by Pierce (1909 and 1914), while other 

 structures have been described in terms relative to the parts of the 

 abdominal segment. 



It is apparently not yet decided how many segments are theoretically 

 comprised in the development of the genital apparatus in either sex in 

 the Hemiptera, but a knowledge of this subject is not necessary to a 

 discussion of their external anatomy, nor does it affect the value of the 

 structures for taxonomic use. The homologies of the parts in these as 

 compared with other insects have not been determined, but it would 

 seem that the Homoptera in general show a far less complicated arrange- 

 ment of abdominal appendages than most of the orders for which these 

 organs have been described. 



The male genital organs of the Membracidae are not covered by any 

 parts of the abdomen proper, altho they are more or less protected by the 

 posterior process of the pronotum in some species and by the tips of the 

 wings in most. Sharp (1890) has noted that in the Pentatomidae the 

 male genital apparatus is exposed and incapable of being withdrawn 

 into the body. He contrasts this with the protected parts in the 

 Coleoptera, and explains the difference on the ground of the different 

 method of copulation in the two orders. Unfortunately this author 

 deals with the Pentatomidae only, and in this heteropterous family the 

 arrangement of the genitalia is very different from that found in the 

 Membracidae and Sharp's excellent figures offer little suggestion of 

 homologies. The exposed genital chamber, or terminal chamber as it is 

 designated by Sharp, is, however, common to both families. This term 

 may be used to designate the external opening of the iwsterior abdomen 

 below the rectum, which contains the structures in question. In the 

 Membracidae it hardly deserves the name chamber in the sense of an 

 inclosed cavity, since the appendages are all comparatively superficial. 



The genitalia are shown diagrammatically in Plate xxxix, 1, 2, in 

 which the first outline represents the parts in their normal position and 

 the second shows the same parts as dissected and spread apart. The 

 tergum of the ninth abdominal segment overlaps and partially surrounds 

 the rectum, which is located at the extreme dorsal angle of the exposed 

 end. Below and on either side are two broad plates which are here termed, 



