GASTROPHILUS HAEMORRHOIDALIS AND OTHER BOTS. 3 
Linnaeus, Fabricius, and De Geer occupied themselves with the 
early classification, and not until 1797, with Bracy Clark, does the 
natural history of the Oestride truly commence. To this historical 
work of Bracy Clark a few additions, many of which are cited in the 
bibliography, have been made by subsequent writers. 
In conformity with the rules of nomenclature and following the 
reestablishment of the Linnaean designation “ intestinalis” by Guyot, 
“ Gastrophilus intestinalis” is given preference rather than “ Gastro- 
philus equi.” 
_ Aside from priority, the specific name “ eguz” is not reliable, since 
there are several spe- 
cies of Gastrophilus 
which infest the 
horse; moreover “7n- 
testinalis” has been 
adopted by a number 
of dependable au- 
thorities. 
SPECIES DIFFEREN- 
TIATION. 
The eggs, larve, 
and adults are SO Fie. 1.—Gastrophilus nasalis: Female. Oviposits com- 
easily distinguishable monly under the jaws of horses. Greatly enlarged. 
= = c (Original.) 
in this genus that it 
does not require a study of detailed descriptions to enable a student 
to determine the species. (Figs. 1, 2,3.) Prof. Garman’s key to the 
wing venation, a reliable index to the species, is here quoted. 
Kry TO WING VENATION OF GASTROPHILUS SPP. 
i. Discoidal cell not closed by a cross vein______-_________________ G. pecorum. 
DISCO dgcellaGlosed iy a, CLOSS: Vel 2 —: =. ae a 2, 
PPI SemMarked > with Drown. 0-2 ee G. intestinalis. 
Misi eCMnO fama Kea) Wath! DELOWRMLS 25 22 2 eis se ba ee 3 
8. Anterior basal cell nearly or quite equal to the discoidal cell in 
SESE SDL pe SS eee G. nasalis. 
Anterior basal cell markedly shorter*than the discoidal 
CEN a Es ae el a er Nas ri G. haemorrhoidalis. 
The cloudy wings of G. intestinalis and its habit of depositing 
upon any convenient portion of the horse where it is not disturbed, 
but most commonly on the forelegs, will enable one to distinguish 
it most readily. ; 
G. nasalis is smaller than G. intestinalis, densely hairy, with the 
thorax yellowish red or rust colored. Its most common place of 
Oviposition is under the jaws, but it is sometimes observed to oviposit 
