(. Sx. j 
musculus), received from Peru, which was also exhibited. The Mstrus 
larva measured one inch by five lines broad at its widest part, and occupied 
almost the whole of one side of the mouse; when extracted its head was 
found towards the posterior legs of the mouse. Specimens of Holochilus 
apicalis, Peters, Hesperomys caliginosus, 'Tomes, and Hesperomys olivaceus, 
G. R. Waterh., all received in the same collection from Peru, were similarly 
attacked and one specimen of Mus musculus contained two larve of the 
Cistrus. 
Mr. G. H. Verrall remarked that in Brauer’s ‘Monographie der 
(Histriden’ there was no mention of any species living on the Muwrida (mice), 
but that in a later paper (Verh. z.-b. Ges. Wien. xiv. 891, pl. xxi. B) Brauer 
had referred to and figured a species of Gistromyia? whose larva had been 
found on a field mouse (Arvicola arvalis, Pallas), at Langenberg (Wurtem- 
berg) by Prof. Hering, occupying quite a different position, however, to the 
specimen now exhibited. 
Mr. H. T. Stainton exhibited two specimens of Char@as graminis, bred 
from the grass-feeding larve from Clitheroe by Mr. F. 8. Mitchell, thus 
surely identifying the lepidopterous larve which occurred in such great 
numbers (¢f. p. xiv ante). Mr. Fitch said C. graminis had also occurred as 
a “plague” in the Thuringian Forest this year, Herr Gutheil recording 
that from twenty-five to thirty specimens of the larvee or pupe were found 
to the square foot, making about seventy millions to the ninety acres 
affected (Hint. Nach. vii. 258). 
Sir Sidney 8. Saunders exhibited specimens of Sarcophaga lineata, Fall., 
another dipterous parasite on locusts in the Troad, whose larvee, feeding 
internally ou the adipose tissues of their victims, had powerfully contributed 
to clear a considerable tract of country from those which had escaped previous 
destruction in the egg by the Callostoma. Several of these larvee were 
extracted from the abdominal region of locusts steeped im spirits sent by 
Mr. Frank Calvert, of the Dardanelles, who found them located at first 
“in the neck and thorax.” Some of those located as aforesaid have been 
retained in situ within the abdominal segments, which a single full-grown 
larva suffices to fill, having its head inversely directed in these specimens, 
ready to emerge therefrom in their adult larval stage and complete their 
metamorphoses in the earth. 
These larvee, as in many other instances, are furnished with two curvate 
retractile hooks emanating below the first attenuated segment,—like those of 
Conops nurtured within the bodies of Bombus, Pompilus, &c., described and 
figured in our ‘ Transactions’ (ser. 2, vol. iv., p. 285, pl. xxviii, 1858); but 
the reniform appendages—‘“ deflexed from the dorsal region posteriorly and 
concave within ”—which the larvee and pupz of Conops exhibit, are absent 
in these, such spiracular processes being replaced by a small but deep 
recess with a glossy smooth rim surrounding the orifice, at the rotundate 
