818 Charles Paul Alexander 



of the wing sheaths. The number of larvae vastly exceeds the number 

 of pupae, and this would seem to indicate that the pupal existence is of 

 very short duration, else this stage would be found oftener. 



Larva. — Length, 12-12.5 mm. 

 Diameter, 0.8-0.9 mm. 



Coloration grayish subhyaline; a large orange area on posterior lateral parts of prothorax; 

 abdominal welts dark brown. 



Form moderately long and slender; thoracic segments gradually decreasing in length from 

 prothorax to mesothorax; abdominal segments gradually elongated to the fifth, thence short- 

 ened to end of abdomen. Ventral surface of meso- and metathorax and of first eight abdom- 

 inal segments provided with a basal transverse welt which is densely set with microscopic 

 points; on dorsal surface these bands smaller, occurring on metathorax and on abdominal 

 segments 2 to 8, not connected with sternal bands except on metathorax and on eighth 

 abdominal segment. Spiracular disk similar to that in Dicranomyia; the usual ventral 

 lobes represented only by two small, dusky, setiferous areas. Spiracles large, elongate- 

 oval, placed obliquely on the sides of a deep split and so capable of close approximation. 

 Anal gills four, each short, tapering gradually to the blunt tip. 



Head capsiile compact, massive, as in tribe. Labrum transversely oval, margin with short 

 yellowish hairs and a larger tuft on either side. Antenna two-segmented, second segment 

 rather stout, cylindrical, slightly arcuate; apical papilla small but high. Mandible broad and 

 flattened, with a small dorsal tooth and a row of five ventral teeth. JVIaxilla generalized in 

 structure, as in tribe. Hypopharj^nx as in Limnobaria, consisting of a roughly circular 

 chitinized collar provided with a crown of stout teeth. Mentum broad, undivided, anterior 

 margin with eleven teeth. 



Pupa. — Length (including breathing horns), 8-9 mm. 

 Length of breathing horns, 1.2-1.3 mm. 

 Width of body, d.-s., 0.85-0.9 mm. 

 Depth, d.-s., 1-1.05 mm. 



Pronotal breathing horns grayish subhyaline; head and thorax with sheaths dark brown; 

 abdomen whitish, hooks and spines brown. 



Cephalic crest small, indistinctly bilobed, not setiferous; front long and parallel; rostral 

 sheath very long and narrow, subtended on either side by sheaths of paraglossae, the latter 

 projecting beyond tip of rostrum and ending almost opposite end of wing sheath; margin 

 of cheeks flattened as in Limnobaria. Antennal sheaths short, ending slightly beyond base 

 of wing pad. Pronotal breathing horns very large and prominent, not contiguous basally; 

 about a dozen breathing pores along dorsal margin. Mesonotum unarmed; wing sheaths 

 ending opposite base of third abdominal segment; leg sheaths ending opposite or slightly 

 beyond midlength of fourth abdominal segment; tarsal sheaths ending about on a level. 

 Abdominal segments 3 to 7 near base with two bands of chitinized hooks arranged in curved 

 transverse rows inclosing an oval transverse area. Cauda chitinized, tergal region produced 

 into two parallel curved hooks bending strongly dorsad. 



Found at Alto Pass, Union County, Illinois, June G, 1919. 



