72 Tur BLOwF.UIES of NortH AMERICA 
series of this species is that more than a single species may be 
represented, but the differences are apparently not of specific 
significance. 
Length. 9-12 mm. 
Distribution. Neotropical: North as far as Cozumel, Quintana 
Roo Province, Yucatan, Mexico, and south as far as Paraguay. 
This species is the most abundant of the genus in the tropical 
rain forests of Central America and may be collected during 
every season of the year. No specimens were collected at eleva- 
tions over 500 feet. They are most numerous in the dense 
tropical rain forests along coastal sections. 
Biology, habits, and immature stages. Egg: Large macrotype, 
2.5 mm. long, 0.75 mm. in diameter, smooth, membranous, with- 
out apparent sculpture. The egg is withheld in the uterus until 
hatched and it is apparently enclosed in a membranous covering. 
Larva. First instar: Length 3.0-8.0 mm. Nearly white, trans- 
lucent, smooth, segmentation not apparent in newly hatched 
larva but obvious in more mature larva. Metapneustic; posterior 
spiracles (pl. 32, C) large, each with two well-defined, nearly 
horizontal, ovate apertures; newly hatched larva with posterior 
spiracles located dorsally in weak depression nearly one-third the 
distance toward the cephalic segment normal in situation in 
more mature specimens. Cephaloskeleton (pl. 32, A and B) with 
pharyngeal sclerites weakly developed but labial sclerites re- 
markably well-developed, divided, eee sclerotized, weakly 
curved, spatulate. 
The developing larva protrudes into open air through the 
genital opening of the female; many female specimens have been 
examined with the larva so exposed. 
Huascaromusca facialis (Aldrich), new combination 
Mesembrinella facialis Aldrich, U.S. Natl. Mus. Proce. 62(11) :17, 
1922. (Type, female from Costa Rica, No. 25248, U. S. 
National Museum.) 
A yellowish brown species with the fourth abdominal segment 
nearly black. 
This species differs in some respects from other species in- 
cluded in the genus Huascaromusca, but too few species have 
been seen to judge the significance of these differences. The 
genotype has the tympanic ridge clearly bare, but this may be 
only a specific character in the genus. 
Female. Head width 16.4; length at antenna and at vibrissa 
6.5; eye height 11.0; epistoma strongly warped forward from 
clypeal plane; clypeus deeply sunken but wide; head height. 
