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 capsule 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. Maxilla generalized in 
structure, as in tribe. Hypopharynx 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 6, 1919. 
