Xo. 0)4] DIPTEKA OF COXXECTICUT : MORPHOLOGY 13 



<^enburg (1892), Patton and Evans (1929). Stevens and Newstead 

 (1907), Stuhlmann (1907), Vogel (1921). and Wandolleck (1894) are 

 of value for the study of various features of the heads of individual 

 Diptera. Descriptions of the sclerites and vestiture of the heads of 

 typical muscoidean flies are given in the publications of Wainwright 

 (1928), Walton (1909), and Townsend (1908).. Various types of an- 

 tennae found in the Diptera are figured in the papers of "Wandolleck 

 (1894), Alexander (1919), Peterson (1916), Patton and MacGill 

 (1925), and Curran (1934), etc. 



1. Modifications of tlie head 



In the diopsid genera Sphyrocephala, Diopdmi and Diopsis^ the 

 lateral regions of the head which bear the eyes and antennae exhibit 

 an increasing tendency to jut out on each side of the head until they 

 finally develop into extraordinarily elongated eye-stalks bearing the 

 e3'es and antennae at their tips, as in the male diopsid Teleopsis shown 

 in Fig. 3, B. In males of the otitid fly, Richardki telescopica^ figured 

 by Curran (1934, p. 20), the eyes are also borne at the ends of long 

 eye-stalks, but the antennae remain in their normal position near the 

 median region of the head. 



In some species of the tipulid genus Hellus^ the head region be- 

 low the eyes is moderately prolonged to form a short ''rostrum" (bear- 

 ing the reduced mouth parts at its tip) which in other species of 

 Helms becomes half as long as the body, while in the genus EJepluin- 

 tomyki the rostrum may be half as long as the body, or it may greatly 

 exceed the body in length (Fig. 3, A). A similar ventral prolongation 

 of the head region below the eyes, bearing the mouth parts at its tip, 

 occurs in the tipulid genus Toxorhina and in the tanyderid genus 

 Per'ni(jueyomyhut. 



In mycetophilids of the Gnorlste type (Fig. 4, D), the region of 

 the head extending along the anteclypeus, «c, is the principal one in- 

 volved in the formation of the elongated rostrum or "proboscis", and 

 the mouth parts, borne at its tip, remain small. 



In the head of a female mosquito (Fig. 3. E), the labrum and 

 mouth parts are the structures which beco)ne greatly elongated, and 

 the head capsule itself is but slightly affected by the process. In this 

 type, the elongation of the labium is effected by the lengthening of 

 the prementum {pm of Fig. 3, E) while the labella, la, are not greatly 

 elongated, as is also the case in the head of the cyrtid shown in Fig. 

 3,C. 



In the type of head exhibited by the tipulid Geranomyia shown in 

 Fig. 4, H, the parts which become extremely elongated are the labrum, 

 Ir, the hypopharynx, hp, and the labial palpi or labella, la. while the 

 rest of the labium and other mouth parts are not greatly affected by 

 the process. The labella are extremely long and slender in Geran- 

 omyia, but Edwards (1931) has described a chironomid, Rhinocladius 

 longirostris, in which the labella are as long as the body, and the la- 

 . bella of this chironomid are probably longer than the labella of any 

 other Diptera. 



