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before. The composition of it is, in fact, essentiaiiy the same in both, the 
last of the seven segments, of which it consists, being imperfectly developed 
and mostly concealed: the only difference is that the seventh segment is 
usually rather more apparent in the species of Sargus than in the smaller 
Chrysomyiie or Microchrysce. 
Xylophagus and Subula might have been most readily distinguished by 
the fourth posterior areolet being open in the former and closed in the latter 
genus. One of the generic characters given for Xylophagus is “tibiae apice 
spinosae” (calcaratas is the more usual term) : this is a character of the 
family at large. The terminal segments of the abdomen in Subula are re¬ 
presented as forming a tubular jointed oviduct (ovipositor is meant); a 
very inappropriate description. 
Tab anus. —The absence of terminal spurs to the hind tibiae should not 
have been overlooked, as this is the only reliable distinction to separate the 
genus from Pangonia. What the author means when he terms the 
antennae “subretusae” in this genus, as also in the two following, is unin¬ 
telligible. 
HiEMATOPOTA. —An essential character of the genus is omitted, the 
presence of a conspicuous recurrent process near the base of the anterior 
branch of the cubital vein; as also the peculiar marking of the wing, in 
all the known species. 
Chrysops. —The presence of the minute terminal spurs of the hind tibiae 
has been overlooked; the phrase “antennae inserted in the middle of the 
front” is as vague and unsatisfactory as when it is said of Hcematopota , 
“antennas inserted in the front of the face.” 
In the family Acroceridce , the presence or absence, and the number of 
the ocelli, are among the most important of the generic characters. 
Acrocera. —“Alulae large, &c.,” should be struck out, as belonging to 
the character of the family; and “ocelli three” should be added, as also 
that the eyes meet below the antennae, and that there is a short proboscis. 
In this genus the antennae are two-jointed. 
Henops. —This name, proposed by Illiger, should yield to Latreille’s 
Oncodes , as Erichson has shown in his Monograph of the family. The 
antennae are two-jointed in this genus also; but there is no proboscis, and 
the mouth appears to be completely closed. Mr. Walker’s account of the 
oral organs seems to be merely a repetition of the old errors, which Erichson 
has rectified. This genus has only two instead of three ocelli; and here 
also the size of the alulae should be excluded from the generic character. 
In the synoptic table of the genera of Asilidce , Dioctria might have been 
