a Genus of Dipterous Insects. 287 
There are other peculiarities of structure, however, in the genus Diopsis 
which contribute to its interest. Of these, the 4 or 6 spines which arm the 
sides of the thorax and the extremity of the scutellum are remarkable. I am 
aware of only one Muscideous insect resembling it in this respect, the T'etanocera 
bispinosa of Wiedemann, which has only two spines on the scutellum. Latreille 
has, however, named an entire Dipterous group (Sératiomide, &c.), from their 
possessing similar scutellar spines, /Votacantha ; but in none of these are the 
sides of the thorax spined*. So also the two spines which arm the lower 
sides of the face, and those placed at the extremity of the four posterior femora, 
are exclusively confined to this genus, whilst the raptorial structure of the 
fore legs is not amongst its least interesting characters. 
Respecting the cHanAcTERs of this genus the most detailed descriptions 
hitherto given are those of Fabricius, Latreille, and Dalman, upon which, 
however, a very careful investigation of the Diopsis Sykesii has rendered a 
few observations necessary. Thus, Dalman describes the ANTENNÆ as “vix 
visibiliter triarticulatoe—articulo tertio subovato—seta terminato ;" whilst La- 
treille correctly describes them as “ compresse articulis tribus, 1mo, minimo ; 
2do, cyathiformi; 3tio, suborbieulato;" incorrectly adding, “ad basin seti- 
gero,"—the seta being inserted on the upper margin of the third joint near its 
extremity. As to the rropHi, the descriptions of Fabricius and Latreille do 
not coincide, and Dalman was unable to examine their structure so as to 
clear up the differences. Fabricius says, “ Os haud prominens, proboscide, 
haustello palpisque. Proboscis magna, membranacea, geniculata, retractilis : 
stipite brevi, cylindrico, capitulo carnoso, bilabiato: laciniis zequalibus, con- 
niventibus. Haustellum absque vagina, seta unica, cornea, setacea, acuta, in 
canalem dorsalem proboscidis recondenda.  Palpi duo, elongati, conici, ad 
basin setze inserti:" whilst Latreille merely observes, * Proboscis Muscarum. 
Palpi breves, cylindrici, subacuminati.” In the Diopsis Sykesii, however, the 
mouth exhibits a more perfect organization than has hitherto been noticed in 
any of the great second division of the Athericerous Dipfera to which it be- 
longs, closely resembling, in fact, the structure of Latreille's first division of the 
* I have more recently:noticed in the collection at the East India House a species of Sargus, brought 
from Java by Dr. Horsfield, the thorax of which possesses lateral as well as scutellar spines. The same 
also occurs in the genus C/itellaria. 
