102 HORSE AND CATTLE FLIES. 
sroove along the under surface.” Details are given at some length by 
Mr. Butler, amongst other points, of the structure of these tubes, 
“which,” he says, ‘‘on account of their superficial resemblance to 
tracheal tubes, are called psewdo-trachea. . . . They are, of course, 
not breathing-organs, but serve as a sucking and straining apparatus 
for conveying to the mouth the juices on which the fly feeds.” —( Loc. 
cit. p. 193.) 
This, in respect of feeding, would not be the use in the case of foot 
service of the Forest Fly, but a ‘‘straining apparatus’? would be 
exceedingly appropriate so placed; and I have ventured to draw 
attention to them, as though I fear I may be merely speculating on 
the uses of apparatus well known to skilled dipterists, yet, if so, I will 
ask excuse, as I have not been able to find description of the appen- 
dages; and in any case the figures of the wonderfully delicate foot- 
apparatus which enables the Forest Fly to make itself so thoroughly 
at home on its hosts will be of interest to many. 
Perhaps I may add that the microscopic slides were prepared for 
me from quite fresh specimens by Mr. J. Pillischer (optician), of 88, 
New Bond Street, London; and the figures—which I think are very 
beautifully executed—were drawn for me by Mr. Horace Knight, of the 
artistic staff of Messrs. West, Newman & Co., 54, Hatton Garden, 
London. 
Hasits or THE Forrest Fty.—The following notes, sent me on the 
2nd of May by Mr. Thomas B. Goodall, F.R.C.V.S., of Purewell Cross, 
Christchurch, Hants, were among the first communications with which 
I was favoured in the past season on the habits of the Forest Fly. 
Mr. Goodall observed that ‘‘ horses bred in the forest take no notice 
of it, though, strange to say, the donkey will never tolerate its pre- 
sence, but will use the most frantic efforts to dislodge the fly. 
‘‘ Most strange horses become accustomed to it in a few days; but 
some never do. I have an old cob (now a pensioner) that I brought 
here from Leicestershire twenty years ago, and even now a Forest Fly 
crawling over him will drive him almost mad. 
‘‘T do not believe that it is the cause of any direct harm to the 
horse, though it does take its nourishment of blood from its host. 
‘A strange horse is frightened because of his inability to dislodge 
the fly, its power of prehension being so great that the horse’s tail is 
powerless to remove it, and it crawls over the body of the horse, and 
does not remain quiescent until it finds a thin part of the skin, where, 
in the Forest ponies, it may sometimes be seen in clusters. The 
favourite parts being round the anus, on the perineum, and on the 
inner parts of the thighs. 
‘‘ When a strange horse has a ‘ Forester’ (as this fly is called locally) 
