66 BULLETIN 66, UNITED STATES NATIONAL MUSEUM. 



have eight primary veins (Xenidse), which become reduced in num- 

 ber to live in the Elenchidae. As Saunders worked out a system of 

 nomenclature for the veins Ms names will be given in parenthesis 

 following those herein adopted. The costa (neura costalis) arises 

 at the base and follows the edge, being sometimes interrupted by 

 the node. The subcosta (neura mediastina) is a light vein immedi- 

 ately beneath and terminating at the node. The radius (neura 

 postcostalis) is often very stout. It is sometimes interrupted at the 

 node, and in one case a very fine vein was noticed branching off at 

 tins point of interruption (Apractelytra scliwarzi). This little vein 

 is evidently the first branch of the radius, and the one most ordinarily 

 seen is the second branch of the radius. The costal area (area cos- 

 talis) lies between the radius and costa and is very much more heavily 

 pubescent than the remainder of the wing. The next primary vein 

 is the medius (neura externomedia) and it is the last arising from the 

 costal stalk of the trachea. Between the radius and medius there 

 often occur one or two detached veins evidently belonging to the 

 medius. These are the first and second branches of the medius [neura 

 la insulata (apicalis) and neura 2a insulata (discoidalis)]. In some 

 cases the fourth branch of the medius is found below the medius 

 and entirely unattached. The median area (superior) lies between the 

 medius and cubitus. The cubitus (neura subexterno media) arises 

 from the anal stalk. Tins is followed by the first anal (neura interno- 

 media), second anal (neura subinterno-media) , and third anal (neura 

 analis). One or more of these are often absent. The anal area (in- 

 ferior) is comprised between the cubitus and posterior edge (margo 

 analis). Saunders called the part between the third anal and anal 

 margin the area analis. 



The legs are isomerous. The front and middle coxal cavities are 

 open behind, while the posterior are closed. The anterior and median 

 trochanters are long and transverse and the posterior rather short. 

 The femora are rather stout, the tibiae slender. The tarsi are two to 

 four jointed and without claws or five-jointed and with two claws 

 (Mengeidse). Each tarsal joint is provided beneath and appendaged 

 apically with a delicate adhesive pulvillus clad with curved hairs, 

 except in the Mengeidse and Myrmecolacidae, in which the first two 

 or three joints are cylindrical. (See fig. 3, on p. 69, nos. 1, 3, 5, 9, 

 11, 13, 15.) 



The abdomen is composed uniformly of ten segments, although 

 the form of some of these segments is subject to variation. Xasso- 

 now (1893) first worked out the true relations of the abdomen by 

 following the younger stages up. He found that the tenth segment 

 bearing the anal pore was ventrally surpassed by the ninth segment 

 bearing the genital pore. The writer's study of Acroschismus 

 Jiubbardi results in the following description : The tenth segment (the 

 podex of Kirby) as a sort of suranal flap overhangs the projecting, 



