12 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 69 



Genus PLANES Rondani 



Planes Rondani, Archivio per la Zoolog., vol. 3. (sep.) p. 9, 1863. For Xylota 



vagans Wiedemann. 

 Syritta of Authors. Genotype, Syritta vagans (Wiedemann), Aussereur, 



zweifl. Ins., vol. 2, p. 101. Planes vagans (Wiedemann) Rondani, Archivio 



per la Zoolog., vol. 3, p. 9, 1863. 

 Syi'itta americana Schineb, Reise de Novara, Diptera, p. 367. — Williston, 



Trans. Amer. Ent. Soc, vol. 15, p. 285, 1888. 

 Syritta mexicana Bigot, Ann. Soc. France, 1883, p. 539. 



The species belonging to this group, as far as known, are con- 

 fined to Tropical America ; whereas the species of Xylota and Xylo- 

 tomima apparently are entirely of Nearctic distribution. The genus 

 is clearly an intermediate group between Xylotomwia {Xylota^ in 

 part) and Syritta. 



DescHption. — General appearance similar to that of the Xylotae 

 possessing yellow abdominal markings. Head broadly elliptical; 

 front of female very narrow; ocellar triangle of male very narrow 

 and elongate ; ocelli well advanced of the occipital margin ; antennae 

 usually rather elongate; arista longer than width of face across 

 middle ; face subcarinate, slightly concave in profile ; usually yellow- 

 ish above anterior oral margin and well covered with silvery pollen ; 

 eyes very large, lower face, between side oral margin and eyes, 

 narrow; body pile short and inconspicuous; metasternum unusually 

 developed, pilose, the male sometimes with spur-like protuberances, 

 hind margin truncate ; hind femur remarkably thickened, keeled and 

 spinose along lower surface; hind tibia at ventral apex produced into 

 a usually long obtuse tooth; abdomen usually elongate and con- 

 stricted at second and third segments; sternites extremely long and 

 narrow ; discal cross vein before or at middle of wing, fairly oblique ; 

 wing villosity normal. 



The following key includes all the species known to the writer. 

 In several cases one of the sexes is missing and this combined with 

 the sexual dimorphism which occurs in the genus makes it advis- 

 able to key the sexes separately. 



KEY TO SPKCIES OF PLANES 



A^. Males. 



B\ Metasternum with a pair of spurs. 



C\ Second tergite largely yellow ; third entirely black. 



D\ Fourth tergite with dense, appressed, golden yellow pile 



(Mexico) paiixilla (Williston). 



D". Fourth tergite with normal whitish pile (Mexico). 



willistoni, new species. 

 C^ Second and third tergites each with a pair of yellow spots. 



D*. Face greenish bronze (Cuba) pretiosa (Loew), 



D". Face black, anterior oral margin yellowish (Costa Rica). 



rondanii, new species. 



