THE CANADIAN ENTOMOLOGIST 155 



genital segments as in figure 2; first genital segment dull orange, darkened 

 anteriorly; claspers and forceps are essentially alike in both species. 



Examination of the figures shows that there is a fundamental likeness in 

 the structure of the accessory genital parts of all four species. 



Table of Species. 



1. Four or more posterior dorsocentrals, posterior tibia very short 2. 



Three posterior dorsocentrals, posterior tibia of normal length 3. 



2. Posterior femur normal, tibia short, but not distorted tothilli, n. sp. 



Posterior femur very large with protuberance beneath bearing a "brush," 

 tibia short and distorted incurva Aldrich. 



3. Anterior clasper reversed S-shaped, penis on long, slender 



base pachyproctosa, n. sp. 



Anterior clasper with distal hook and large expanded base, penis on short 

 base pachyprocta (R. Parker). 



Metoposarcophaga tothilli, n. sp. 



Holotype (male). — Collection of R. R. Parker. 



Male. — Parafrontals and genje silvery grey ; vestiture of back of head black 

 except for some light coloured hairs just below foramen (difficult to see) ; lateral 

 verticals present, greater ocellars well developed, section III of costa about equal 

 to section X; leg vestiture short; anterior face of posterior femur with only 

 upper row of bristles complete ; posterior tibiae very short, much shorter than 

 either femur or tarsus; anterior acrostichals present; four pairs posterior dorso- 

 centrals (sometimes five) ; genital segments dull orange except that first is 

 darkened anteriorly. 



Length 6-10 mm. 



Head viewed from side parafrontals and gense with dark reflections; trans- 

 verse impression same colour as genae. Breadth of front at narrowest part about 

 three-fifths eye width; cheek height approximately three-sevenths that of eye. 

 Front very prominent; width of frontal vitta variable but at narrowest part of 

 front at least twice width of each parafrontal. Second antennal segment dark; 

 third about twice length of second ; arista short plumose about to middle. Vesti- 

 ture of back of head black. Gena with scattering hairs above, below with a 

 row close to lower eye orbit. 



ChcEtotaxy. — Lateral verticals present; vibrissae inserted slightly above 

 line of oral margin; greater ocellars well developed; frontal rows of bristles 

 extending to or slightly below base of vitta, the lower few pairs divergent from 

 edges of vitta. 



Thorax. — Vestiture of mesonotum black, cilia-fike, slightly reclinate. 



Wings. — ^Anterior cross- vein more basal than end of first longitudinal; 

 third vein bristly; costal spine vestigial; section III of costa practically equal to 

 section V; calypters whitish, fringed with white hair. 



Legs. — Dark, vestiture short. Anterior face of posterior femur with com- 

 plete upper row of bristles, intermediate row absent, lower row with a few rather 

 weak distal bristles; tibia ver>' short, beardless, about three-fourths length of 

 femur, much shorter than tarsus, middle femur without "comb." 



Chcetotaxy,. — Well developed. Anterior acrostichals present; inner pre- 

 suturals absent; four pairs posterior dorsocentrals (sometimes five); prescutellar 



