156 ERNEST A. BACK. 



varying degrees. Thorax with a high arch, the anterior part 

 of the mesonotum usually projecting over the pronotum; the 

 scutellum very small. Dorsum with two well developed 

 bristles on either side, one presutural, the other post-alar, upon 

 the callosity. Abdomen long and very slender, at least from 

 four to six times the length of the thorax, usually with a dis- 

 tinct bend at the union of the first and second segments; at 

 the tip, sometimes broader in the male, in the female oc- 

 casionally very prominently swollen; without bristles except 

 on the posterior margins of the first segment. Legs rather 

 slender, the front tibiae without a terminal claw-like spur; 

 the hind legs much longer than the anterior pairs, their femora 

 usually very slender on basal portion, on the distal portion 

 usually gradually or suddenly incrassate, but sometimes 

 scarcely thickened; hind tibiae sometimes very long and slen- 

 der. Femora without bristles except at tip above; the tibiae 

 with few, the tarsi with more, bristles; tarsi usually bent back 

 upon themselves. Claws strong, pulvilli wanting; the single 

 empodium of each foot bristle-like, of varying length, but 

 sometimes absent. Wings shorter than abdomen; sometimes 

 considerably attenuated on basal portion; marginal cell open; 

 five posterior cells present ; all open ; the fourth petiolate, sub- 

 sessile or sessile; anal cell open. 



Type. — Asilus tipuloides Fabricius. 



Prof. M. Bezzi states in Wien. Ent. Zeit., Vol. 26, page 55, 

 that Gonypes should take priority over Leptogaster. Latreille, 

 in the fourth volume of his Histoire, divides the Asilidae into 

 four groups of which the last is " Asiles tipul oides" with Asiles 

 tipul oides F. as an example. But Latreille did not give to this 

 group the generic name Gonypes until the year 1804, when 

 the fourteenth volume of his Historie appeared. Meanwhile 

 Meigen published and described Leptogaster in 1803 in Illiger's 

 Magazin, and gave as the type Asilus tipul oides. According 

 to the Law of Priority of the International Code of Nomen- 

 clature, page 35, article 25, Leptogaster must still hold the 

 priority. 



