82 PROCEEDINGS OF THE ACADEMY OF [Part I 



in structure as in phorodenia, there being two elongate, blade-like 

 structures that are blackened at their tips. The penis-guard itself 

 is flattened, the margin produced into an acicular spine; at the base 

 of the penis-guard is a small bottle-shaped appendage with the 

 neck heavily blackened. On the ninth tergite are two cylindrical 

 arms as in phoroctenia, these bearing a comb of six powerful curved 

 teeth, shortest proximally, gradually lengthening toward the out- 

 side; the outer lateral angles are replaced by long yellowish hairs. 

 In the slide mounts of phorodenia these arms are directed cephalad 

 and the teeth are on the lateral side but this condition may be due 

 to torsion in mounting. The figures show the hypopygia as they 

 appear on the slides. 



Habitat. — Peru. 



Holotype, cf, Iquitos, May 17, 1920 (H. S. Parish). 



Paratopotype, d", May 15, 1920. 



Gonomyia (Leiponeura) crepuscula sp. n. Plate IV, figs. 5, 5A. 



Male. — Length about 3.7 mm.; wing 3.8 mm. 



Generally similar to G. (L.) phorpdenia, sp. n., differing as follows: 

 Sci ending a short distance before the origin of Rs; basal deflection 

 of Cui a short distance before the fork of M. Male hypopygium 

 (Plate IV, Figs. 5, 5A) with the pleurites long and slender, clothed 

 with bristles as in phorodenia. A single pleural appendage, this 

 appearing as a short curved chitinized horn, the tips acute. Gona- 

 pophyses and penis-guard forming a complicated mass as in phoroc- 

 tenia, there being two elongate organs, one slightly bent at the 

 apex and heavily blackened, the second, which is presumably the 

 penis-guard, pale, narrowed to the acute tip. Besides these there 

 is a blackened flattened plate surrounding the penis-guard. The 

 general arrangement of teeth on the ninth tergite is here approxi- 

 mately as in phoroctenia and ctenophora but the number of teeth is 

 greatly reduced, there being but three or four of these, the outer- 

 most being very much more powerful than any of the others, the 

 inner angle clothed with delicate appressed hairs. 



Habitat. — Peru. 



Holotype, cT, Napo River, June 15, 1920 (H. S. Parish). 



Gonomyia (Leiponeura) bispinosa sp. n. Plate IV, figs. 4, 4A. 



Rostrum obscure reddish orange; antennae dark brown; pleura 

 pale yellow, heavily pruinose with snowy white, the longitudinal 

 stripe being very broad and ill-defined; knobs of the halteres yellow; 

 male hypopygium with the pleural appendages two in number, 

 similar to one another in shape, cylindrical, curved, each tipped 

 with a powerful curved spine; penis-guard relativelj^ long and slender. 



Male. — Length about 3 mm.; wing 3.3 mm. 



Rostrum obscure reddish orange. Antennae with the second 

 scapal segment enlarged, subglobular, dark brown, the lower sm- 



