214 SUMMARY of' CURRENT RESEARCHES RELATING TO 



embryonic development proceeds — e.g. some Tachinarise, Dexiidse, all 

 the Sarcophagidas, various Anthomyidae (e.g. Musca larvipara and 

 Mesemhrina meridiana). Second, there are those in which the larvaa 

 pass all their time in the maternal uterus, some being born as larvae 

 (e.g. Glossina), and others as pup^e (e.g. Bippobosca, Melophagus, and 

 Ornithomyia). The larvag of the second set exhibit some special 

 characters related to the intra-uterine nutrition. Thus the bucco- 

 pharyngeal apparatus is reduced to the basilar plate, a convergence to 

 which is seen in some parasitic larva3. Moreever, the salivary glands 

 disappear, the mid-gut does not communicate with the hind-gut, and 

 the respiratory apparatus is metapneustic in all the three stages of 

 larval life. 



Portchinsky has interpreted the viviparity as an adaptation arising 

 in coprophagous forms, where it is advantageous in reducing the 

 coprophagous period. Roubaud gets back to primary causes in 

 associating viviparity with rich diet and high temperature. Keilin 

 regards this as too simple, for the conditions might simply lead to more 

 eggs and more ovipositions. It must be remembered, moreover, that 

 the larva is as peculiarly adapted to its intra-uterine life as a parasitic 

 larva to its host. 



Structure of Ptychoptera albimana.* — Emile Topsent describes 

 some of the minute structures of this fly (Nemocera), e.g. the structure 

 of the egg-envelope, the sets of the larva, the so-called tracheal gills 

 which have a dubious respiratory significance, and the otocysts. 



Habits and Parasites of Common Flies.t — G. S. Graham-Smith 

 has reached the following conclusions as the outcome of prolonged 

 observation and experiment. In the common species the very great 

 majority of individuals pass the winter as pupae, or more rarely as larvae 

 which pupate early in the spring. The pupre or larvae lie under shelter 

 on the surface of the ground, or more commonly at a depth of two or 

 three inches. A very small and unimportant minority of both sexes, 

 emerging from pupte late in the autumn or even in the winter, possibly 

 survive as adults till the spring. It is very improbable that many of 

 the females with this history are impregnated in the autumn, or that 

 most of them reach sexual maturity much earlier than the broods 

 emerging in the spring. The wintering habits of Musca domestica 

 are still obscure. 



The time occupied by the various stages between the rupture of the 

 puparium and full formation varies with the temperature. The majority 

 of the specimens of each species only emerge from " winter " pupse after 

 the mean temperature of the surrounding materials reaches a "critical " 

 point. This is about 48°-50° F. for Galliphora erythrocephala, Fannia 

 mamcata, F. scalaris, and about 63° F. for Ophyra leucostoma. In 

 several species the majority of males emerge before the females. Flies 

 emerging from " winter " pupae seem to be the most hardy. Many of 



* Arch. Zool. Exp6r, Iv. (1916) Notes et K6vue, No. 5, pp. 81-94 (9 figs.), 

 t Parasitology, viii. (1916) pp. 440-544 (8 pis., 17 figs., -and 9 charts). 



