64. THE BLOWFUIES OF NortTH AMERICA 
toria; the vas deferens is elongate and narrowed apically, the 
anterior sixth is thickened. The hourglass-shaped testes and the 
ego-shaped vehicular glands are very small; the latter are about 
half as large as the former, and, with the vasa efferentia, are en- 
closed in tissue hoods. The vasa efferentia are about as long as 
the testes. 
Giglio-Tos (1893) designated Musca quadrilineata Fabricius 
as genotype of his genus Mesembrinella. His quadrilineata was 
a misidentification. Aldrich (1922) redeseribed the quadrilineata 
of Giglio-Tos (nee Fabricius) as Mesembolia bellardiana. Town- 
send (1931), considering Mesembrinella to apply to quadri- 
lineata Giglio-Tos, not Fabricius, proposed Humesembrinella, 
naming quadrilineata Fabricius as genotype Most of the species 
treated by Aldrich (1922) under the name of Mesembrinella be- 
long in the genus Huascaromusca Townsend, which has (cru- 
ciata Townsend) =xanthorrhina Bigot as genotype. Townsend 
saw Giglio-Tos’ and Fabricius’ type specimens and Aldrich saw 
the Fabrician type. 
Mesembrinella and Mesembolia do not occur in North America 
so far as I know. 
KEY TO GENERA AND SPECIES OF NORTH AMERICAN 
MESEMBRINELLINAE 
1. Posthumeral and preacrostichal bristles present........ 2 
Posthumeral and preacrostichal bristles absent .......... 
Te e's ee Promesembrinella semrflava (Ald.), p. 65 
2. Two preintraalar bristles present’ ........').... 7) ee 3 
Presutural -intraalar bristles. absent ..7...... ) ose 5 
3. Sixth section of costa less than one half as long as pre- 
ceeding section; width of parafaciale opposite lunule 
0.30 or less of distance between vibrissae ............ 4 
Sixth section of costa more than one-half as long as pre- 
ceding section; width of parafaciale opposite lunule 
0.40 of distance between ae ade s ogee 4. +e) 
4. Front of male 0.07—0.08 of head width, with a small 
proclinate frontoorbital bristle nearly opposite fore- 
most ocellus; female with only one proclinate fronto- 
orbital bristle.. +... eee ded ates ae Ae z 
