1924 ] North American Species of Opacifrons and Pteremis 129 
the bristles somewhat reduced; middle femora with a single 
preapical anterior setse, middle tibiae with four extensor, one on 
basal third, and two on apical fourth, and no flexor bristles, 
middle tarsi with a small seta on flexor surface near base; hind 
metatarsi as thick as tibiae at apex and one-half as long as the 
much more slender second joint. Wings hyaline or but slightly 
yellowish; veins brown; costa extending slightly beyond third 
vein, second section one and one-fourth times as long as third; 
second vein ending beyond the outer cross vein; basal section of 
third vein one-third as long as the last section of second vein and 
nearly two times outer cross vein; last section of third vein 
gently curved, ending a little before wing-tip; fourth vein 
reaching margin of wing; fifth vein produced considerably 
beyond outer cross vein. Abdomen piceous, flat oval; hind 
margins of segments narrowly yellowish; second segment not 
much longer than third. Halteres whitish. Length: 2 mm. 
Type. — Female: Austin, Texas; Oct. 29, 1899 (Melander). 
Paratypes. — Two specimens from Illinois (111. Univ.) 
Leptocera (Opacifrons) coxata Stenhammar (Fig. 7). 
Stenhammar: Coprom. Scand. 396 (138) (1855). {Limo- 
sina ) . 
Duda: Abhand. Zool.-Botan. Ges. Wien. X. I. 85 (1918). 
(Limosina). 
Pusio Zetterstedt: Dipt. Scand. VI. 2496 (1847). {Limo- 
sina) . 
Pumilo Zetterstedt: Ins. Lapp. 771 (1838). (Limosina). 
Septentrionalis T>Bh\: Berl. Sb. Ges. Natf. Freunder. (1909). 
(Limosina ) . 
Nigricoris Dahl; Berl. Sb. Ges. Natf. Freunde. 375 (1909). 
(Limosina). 
Forty seven specimens from the following localities: 
Washington: Bellingham, Lake Whatcom, Nahcotta, Lake 
Cushman, Ilwaco, Granite Falls, Sultan, La Center, Tacoma, 
