32 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bllll. 



though it is not reiiarded as a part of the pharyn<real region by most 

 recent investigators. Peterson (11)16) considers that the posterior re- 

 gion of the fulcrum is formed by the basal portions of the epipharynx: 

 and hypoi^harynx, while its anterior portion is formed by the "tor 

 mae", although the external sclerite, ac, of Fig. 4. B, E and J, which • 

 Peterson designates as the ''tormae" in higher Diptera apparently rep- 

 resents the anteclypeus, or the united anteclypeal sclerites (clypeites), 

 of the orthopteroid insects. The fulcrum is boi-ne at the basal, or 

 dorsal, end of the labrum in many Orthorrhapha Brachycera: but in \ 

 the Cyclorrhapha it becomes intimately associated (anteriorly) witli i 

 the external anteclypeus, ac^ which acts as a supporting plate for the ' 

 fulcrum, while permitting the folding movements of the basal por- " 

 tion of the proboscis, or oral cone, within Avhich the fulcrum is sit- 

 uated. The food pump and other structures connected with the ful- 

 crum will be described under the discussion of the feeding mechanism 

 of the higher Diptera. 



The mandil)les of the Diptera are slender, elongated structures, 

 resembling the mandibles of the Mecoptera very closely. They are 

 present in the females of some Psychodidae (such as Phlebotomus), 

 Dixidae, Culicidae, Ceratopogonidae, Simuliidae (present in both 

 sexes), Blepharoceridae and Tabanidae, etc., but have been recorded a> 

 occurring in the males of only three families. Peterson has found 

 them in the males of two species of Simulhim: Wesche has recorded 

 their occurrence (as abnormalities) in a few male mosquitoes: and 

 Jobling describes them in males of Culicoides puUcarh. The man- 

 dibles are usually slender, stylet-like structures, but in certain bleph- 

 arocerids they are blunt at the tip, and are serrate along the mesal 

 margins, which fit against the lateral margins of the hypopharynx. 

 They are much elongated in the culicicls (Fig. •^>. E), and are <|uite 

 long in the tabanid Pangonia longirosfris. In (JuJico/des and Tolxnnis 

 (Fig. 4, (i), the mandibles, md^ intervene between the hypopharynx. 

 liy^ and the labrum, Zr, and ventrally close the food channel, whose 

 dorsal and lateral walls are formed by the labrum, Ir^ although the 

 hypopharynx usually forms the floor of the food channel in the higher 

 Diptera. The mandibles likewise intervene betAveen the labrum and 

 the hypopharynx in such simuliids as Sinudiu'nv hirtipes. 



The mandibles are attached to the head capsule between the base 

 of the labrum and the base of the maxillae, and are usually associated 

 with the anterior arms of the tentorium. Unless the mandibles aie 

 identified by the location of their points of attachment to the head (in 

 front of the base of the maxilla, and behind the base of the labrum), 

 all sorts of structures may be mistaken for the mandibles, such as the 

 epipharyngeal prongs of the Dolichopodidae (Langholfer, 1888), the 

 labral hooks of the Simuliidae (Smith. 1890), the maxillary stipes of 

 Mtisca, (MacCloskie, 1880), and the sclerotized bands of the labium in 

 various Diptera (Wesche, 1909), etc., so that the importance of this 

 feature should be emphasized very strongly. 



The maxillae of the primitive Diptera (Fig. 2, K) are extremely 

 like those of the mecopteron Nannocho/^fa (Fig. 2.1), and are made 

 up of a laterally directed basal segment, or cardo, ca (Fig. 2, K), an 



