90 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bull. 



Psj'chodidac, and in certain Mycetophilidae, etc., it becomes atro- 

 phied. In the tipulid genus Tipula (Fig. 10, A) and in many Myce- 

 tophilidae, etc., the ninth sternite is large and tends to unite with the 

 basal segments of the genital forceps. In the Trichoceridae, on the 

 other hsmd, and in such tipulids as Macrocera and in the tanyderid 

 Tanyderus forciyatus. the ninth sternite is separate from the basal 

 segments of the genital forceps, which, however, tend to unite basally 

 in these Diptcra. Since the genital forceps represent f orcipate para- 

 meres (instead of coxites and styli as de Meijere, 1919, and other 

 recent investigators maintain) their segments may be referred to as 

 the basimeres and distimeres to indicate this fact. The descriptive 

 designations basistyles and dististyles have long been applied to the 

 basal and distal segments of the genital forceps in male Nematocera, 

 liowcA^er, and there can be no serious objections to the use of these 

 terms in referring to the parts in male Nematocera. 



In the tipulid shown in Fig. 7, J, the "basistyles", cxi^ do not unite 

 with the ninth sternite, but are distinct, elongated structures like those 

 of the culicid shown in Fig. 7,H (compare also Fig. 11, A). In the 

 tipulid shown in Fig. 7, J, the "basistyles" bear mesal processes, ?'&, 

 called interbases, and the "dististyles" are divided into an outer por- 

 tion, ot^ and an inner portion, m, called the outer and inner dististyle 

 by Alexander. Although the division of the "dististyle" into an outer 

 and inner dististyle is quite characteristic of the Tipulidae, it rarely 

 occurs outside of this family of Nematocei-a, although certain Tricho- 

 ceridae and the fossil tanyderid Macrochilc have a forked dististyle, 

 from which type the divided dististyles may have evolved through a 

 deepening of the fork and a separation of its arms. In the recent tany- 

 derid genus Peringueyomyina^ the basistyles and dististyles are ex- 

 tremely slender and elongated, and attain the greatest length occur- 

 ring in any of the Diptera. 



In discussing the structural details of the parts of the ninth seg- 

 ment, etc., in the males of the lower Diptera. the condition occurring 

 hi a typical culicid, such as the one shown in Fig. 11, A, will serve to 

 illustrate the character of the parts in a typical male nematoceran, 

 smce the structures of the ninth segment are quite well developed in 

 male culicids, and considerable attention has been given to the struc- 

 tures of these insects because of their economic importance. The 

 following description of the parts of the ninth segment of a male 

 mosquito is based upon the work of Edwards (1920), Matheson (1929), 

 Freeborn (1924), and Herms (1939), whose terminology has also been 

 adopted here with a few changes to brino- it into harmony with the 

 usage of other entomologists. The terms applied to the parts by other 

 investigators are also listed for comparison. 



The inversion of the ninth segment- (and proctiger) in male 

 mosquitoes IS shown in Fig. 11, B, which is taken from the paper by 

 Jidwards (1920). who has corrected his own earlier misconceptions 

 m the matter, and also the misinterpretations of Brolemann (1919) 

 ancTojher earlier investigators who did not realize that an inversion 



» According to Christophers, the eighth segment is also inverted in male mosquitoes. 



