26 ©. R. Osten Sacken: on Mr. Portchinski's publications 
difference that the larva, when laid by HZ. strigosa, although large, 
is still in its first stage, and therefore has not grown within the 
body of the mother; it passes its three stages outside of it. 
Musca corvina is exceedingly common in the Crimea and the 
Caucasus. Early in the spring (rarely in summer) specimens were 
observed that multiplied according to the mode already explained, that 
is by laying about 24 eggs with their peculiar appendages. Towards 
the end of the spring, and in summer almost exclusively, specimens 
were taken, subject to an entirely different process of propagation. 
Within the matrix-like expansion in the body of the female a single, 
very large egg, is found; it has the ordinary oval shape, without 
any appendages (fig. 8). It is very like the egg of Dasyphora pra- 
torum in shape, but is larger (although the imago of M. corvina is 
smaller than the Dasyphora); it is in its first stage, as is proved 
by the shape of the stigmata; like the larva of D. pratorum it 
growsı) within the body of its mother, “but passes immediately into 
the third stage, with its characteristic spiracles.. This, as far as 
known, is the only instance of a shortengd larval development among 
viviparous species, as they usually undergo the three stages. Sup- 
posing therefore that the specimens observed belong to the same 
species, of which, after careful and repeated comparisons, no doubt 
was entertained, Musca corvina has two different modes of larval 
development; one seems to prevail in the north, the other in the 
south; the latter may be due to the increased numbers of copropha- 
gous species in the southern regions. Musca corvina thus forms 
the connecting link between the flies to which either of these modes 
is exclusively peculiar. 
Hitherto the Pupipara had an isolated position among the 
Diptera. The modes of larval evolution of Musca corvina and Da- 
syphora pratorum, discovered by Mr. Portchinski bridge over the 
interval. He even ventures the hypothesis that the Pupipara began 
by being coprophagous in their larval state, and laid an almost full- 
srown larva, like that of the two above-mentioned flies. Later, owing 
1) Mr. Portchinski observes at this place that as his researches 
are not quite eompleted he cannot as yet stop to examine some im- 
portant questions, for instance: on what do larvae feed in the body 
of their mother? He did not notice in M. corvina Q that large de- 
velopment of the adventitious glands which, according to Leuckart, 
secrete the food of the larvae of Pupipara. It is also worthy of 
notice that the larvae of M. corvina and D. pratorum when squeezed 
out of the body of a female come out with their tail first, while in 
the Sarcophagae they emerge head foremost, 
