442 
Melinda cognata Meigen 
junction of the mid- and hindgut. The salivary glands ( s.gl .) are elongated, 
extending to nearly half of the length of the larva, their posterior ends being 
embedded in a patch of a fat-body. 
(e) PlJPARIUM AND PUPA. 
The puparium (PL XXIII, fig. 5) is of a brown colour, oval and with 
clearly marked segments. The prothoracic spiracular horns ( h .) of the pupa 
emerge from the puparium through a pair of holes on its latero-dorsal side 
near the intersegmental space which separates the first and the second abdo¬ 
minal segments. These horns (PI. XXV, fig. 19) bear a great number of small 
spiracular papillae and each horn communicates with a long “ felt-chamber ” 
(f.c.) which, near its basal portion, inside the puparium, bears an internal 
spiracle (i.sp.). This latter has the form of a bifurcated tubercle bearing 
papillae upon each process. 
IV. THREE OTHER FLIES LIVING UPON HELICELLA 
VIRGATA DA COSTA. 
(a) Melinda sp. probably M. gentilis (R.-D.) Verrall (1912) 1 . 
In the kidney of several living specimens of Helicella virgata there occurred 
a first stage larva of another Calliphorine of which unfortunately I could not 
obtain either the other stages or the adult. This larva occupied the same 
position in the host as the larva of M . cognata and very often the two occurred 
simultaneously in the same host. 
The anatomical study of this larva revealed its striking resemblance to 
that of M. cognata ; in fact it differs from the latter only in the form and the 
size of the external cuticular hooks or spines and a few details in the structure 
of the buccopharyngeal organs. As shown in PL XXIV, fig. 8, the medio-dorsal 
sclerite or labrum (Lbr.) is more prominent, pointed, and curved dorsally; the 
lateral hooks ( l.h .) are larger and more strongly chitinised. It is very probable 
that this larva belongs to Melinda gentilis which is also a very common species 
in England. The fact that these larvae occur less commonly in H. virgata , and 
are always killed by the larvae of M. cognata indicates that this snail is not 
their usual host. As on the other hand the different species of snails which 
I collected with H. virgata did not contain this larva, it is possible that the 
real host of M. gentilis is a Limax or an Arion as the slugs were common in 
all the places where I collected the H. virgata. 
( b ) Sarcopiiaga nigiu ventris Meig. 
Bottcher, in his paper on the genus Sarcophaga (1913, p. 367) quotes 
Villeneuve as authority for the statement that Prof. A. Giard, in September 
1906, bred S. nigriventris from a snail, H. cantioniformis , collected near Wime- 
reux in the Pas-de-Calais. 
1 Melinda gentilis R.-D. described by Verrall (1912) = cognata, of Schiner and Strobl. 
