568 PROCEBDINGS OF THE XATIONAL MVfiEVM. vol. xxxvi. 



Hymenoptera. The first abdominal segment is known as the mediaji 

 segment (" segment mediaire " of Latreille) and can always be identi- 

 fied by its spiracles (160, 1G4, 167, 169, ISp). 



7. Tegula? of fore wings developed as in Diptera into large scale- 

 like plates overlapping humeral, angles of wings (160, 161, 163, 169, 

 170, 205, 206, Tg). In hind wings they are hairy pads as in Orthop- 

 tera (207,209, Tg). 



8. Four axillaries nearly always present as in Orthoptera (205, 206, 



207, 208), the first and fourth articulating with notal wing processes. 



9. Head of costa in fore wings (205, 206, 208, C) separated as a 

 humeral plate with head of subeosta {Sc) attached. Subcosta {Sc) 

 a separate vein in fore wing of Sirex (206), in other forms (205, 207, 



208, Sc) shortened to a basal piece between bases of costa {C) and 

 radius {R) and fused with the detached costal head (206, 207, 208). 

 In hind wing of Peps'is (209) bases of the costa {('), subcosta (*S'c), 

 radius {R)^ and media {M) all fused into one common head. 



There is nothing in the basal structure of the veins that would dis- 

 credit Comstock's interpretation of the Ilymenopteran venation, 

 thougli it probabl}^ does not indicate whether M is fused with R or 

 is lacking. 



XIV. niPTEUA. 



Species studied. — TloJorusia grand is (174—178, wing base 210, base 

 of halter 211), Tipulid pupa (173), Tipulida?; Tahaniis atratns (179, 

 180), Tabanida?; CaU'ipliora i^omitoria (wing base 212) Muscidse. 



Characteristics. — 1. Two cervical sclerites present on each side of 

 neck in Ilolorusia (174) and Tcd>anus (179), and several ventral 

 sclerites in the latter and in Ccdlipliora. 



2. Prothorax reduced but ejoisternum and epimerum (17-1, 179, Eps, 

 E pm) present, and in Ilolorusia, pronotum (174, N.^) formed of two 

 distinct subdivisions {set and scl). 



3. Trochantin absent in all three thoracic segments, imless the 

 small plate (174, 179, Tnf) of the prothorax is a rudimentar}^ tro- 

 chantin. 



4. In meso- and metathorax of Ilolorusia (174) each sternum {S^ , 

 /S'n , S._^) presents a precoxal and a postcoxal plate connecting with 

 the episternum (Eps) and the epimerum (Epm) respectively. This 

 is true only of the mesosternum {S^ , S.^) of Tahanus (179). 



5. Mesopleurum of Ilolorusia of simple, typical structure (174, 

 176, 178) ; but in Tahanus (179) and in all higher Diptera episternum 

 divided into a large anterior plate (eps), and a less conspicuous pos- 

 terior part (Eps) entering into formation of wing process {WP). 

 The relation of the anterior plate (^7^) to the first spiracle (Sp.^) 

 and to the other neighboring j^arts is so nearly identical with that 

 of the single, undivided episternal plate of Ilolorusia (174, EpSo) 



