520 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iob 



Genus Neurorthus Costa 



Neurorthus Costa, 1863, p. 32.— Navds, 1935, p. 19. 

 Sartena Hagen, 1864, p. 41. — McLachlan, 1881, p. 89. 



Large, miiltiveined spongilla-flies. 



Genotype: Neurorthus iridipennis Costa, by monotypy (Costa, 

 1863, p. 33). 



Head: Antenna with basal segment sometimes almost as broad as 

 long, slightly convex on inner margin, second segment shorter and 

 considerably narrower than basal segment; segments of flagellum 

 smaller; vertex convex, sometimes with large mound in center, 

 median sulcus on vertex pronounced; face longer than in Sisyra, deep 

 transverse frontoclypeal depression, anterior margin of clypeus almost 

 straight; labrum bilobed with anterior median concavity, convex 

 laterally; postoccipital margin of foramen slightly convex medially, 

 concave laterally on each side; maxillary palpi with basal two segments 

 short, third slightly longer than fourth, fifth narrow, cylindrical to 

 midpoint, then tapering and narrowing considerably and acute at 

 apex (fig. 7,j) ; labial palpi with terminal segment cylindrical, narrow- 

 ing and acute at apex, sometimes extended. 



Thorax: Pronotum narrower anteriorly, then broadening and 

 rounded laterally, overlapping cervicales, posteriorly narrowing again, 

 distinctively marked and grooved; meso thorax with prescutum large, 

 almost same size as mesoscuteilum ; lateral lobes of mesoscutum slightly 

 narrowed, oblique. Legs with first tarsal segment longest, fourth 

 shortest. 



FoREwiNG (pi. 3, fig. 3): Costal area with numerous, sometimes 

 forked cross-veins, sometimes as many as 24 before pterostigma; 

 subcostal area with a basal subcostal cross-vein, and apparently a i 

 second subcostal cross-vein under pterostigma; Sc and Rl appearing ; 

 separate at apex, joined by the second subcostal cross-vein; Rs^-MA 1 

 separating off from Rl near base and coalesced for a longer distance 

 than in Sisyra; free stem of Rs usually with two main forks, R4-f-5 

 separating off near longitudinal midpoint of wing, R2 and R3 forking ; 

 a short distance beyond; basal piece of MA usually distinct at base, 

 MA deeply forked, dividing into two branches at about or slightly 

 basal to level of point of junction of Sc and Rl ; MP forking into 

 MPl+2 and MP3+4 near separation of Rs from MA; MPl+2 and I 

 MP3+4 with terminal forks under pterostigma; Cul separating from i 

 Cu2 near base of wing; Cul with marginal branches frequently forked; : 

 Cu2 sometimes, 1st and 2d A usually, and 3d A sometimes forked; 

 usually most veins forked at margin except Cu2 and some costal 1 

 cross-veins; three radial cross-veins; usually one or two sectoral cross- 



