42 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
tially parallel; while in species of Sarcophaga they show considerable 
range in size, shape, and vestiture. The vestiture is always hairy and 
decreases in length posteriorly. On the third plate it is shortest, and 
either erect {Ravinia spp., Sarcophaga sp. nov., etc.) or decumbent 
{Boettcheria spp., Sarcophaga haemorrhoidalis, etc.). Erect is used in 
contradistinction to decumbent, but vestiture so classed may incline 
slightly backward. When decumbent, the hairs are scattered and 
comparatively less numerous, especially along the mid-ventral line. 
In Sarcophaga haemorrhoidalis the vestiture is short on the second 
plate as well as on the third but erect on the former. The first plate 
is ordinarily angular and either square, rectangular, or trapezoidal. 
In one species of American Sarcophaga its sides are strongly convergent 
backward and the posterior margin narrower than the adjoining mar- 
gin of the second plate. The sides and hind margins of the second 
and third plates are more or less rounded as a rule. These plates are 
also usually smaller than the first except in Boettcheria. In Sarco- 
phaga tuberosa sarraceniae (Riley) all the plates are square and of 
approximately equal size. The characters of the fourth ventral plate 
are fully as constant as those of the genitalia and are figured for all 
species. Their color is usually that of the genital segments though 
they are sometimes concolorous with the fourth notum. The basal or 
anterior portion may be short or long, roundly or sharply ridged, when 
viewed in profile straight or knobbed at the posterior end, or flat. 
The lamellae are short or long, narrow or wide, with or without pollen, 
with or without flap-like appendages, hairy or bristly, approximated 
or wide spread, fixed or freely movable, with or without 'brushes,' 
or fused. In accordance with Bottcher's usage, the term 'brushes' 
refers to surface not border bristles. ]\Iany of these characters are 
available for specific use without pulling out the genitalia. For 
instance, there are but three species which show the basal portion 
of the plate knobbed posteriorly: S tuberosa sarraceniae (Riley), andS. 
tuberosa exuberans (Pandelle), and an undescribed American species. 
If examination of a specimen shows the knob, the possibilities are at 
once limited to the above. The presence of parallel ' brushes ' on the 
inner part of the lamellae indicates either Ravinia communis or R. 
penicidata, which can then be easily separated by the number of post- 
sutural dorsocentral bristles. 
In Sarcophaga tuberosa sarraceniae (Riley), S. tuberosa harpax 
(Pandelle), and S. tuberosa exuberans (Pandelle) the dorsal portion of 
