54 FAMILY MUSCID/E. 



flies, Flies of which the larvte are internal parasites of cater- 

 pillars, etc.), the imago is enabled to escape by the splitting off 

 of a cap from the cephalic end of the puparium. 



The family Muscid£e in its widest sense is by far the most 

 numerous in genera and species of the whole order. It is 

 divided into two main divisions, Calyptratai and Acalyptratpe ; 

 in the former of these the squama, or membranous scale, situated 

 on the thorax behind and beneath the base of the wing, is 

 sufficiently large to conceal the halter, the little club-shaped 

 organ that projects beneath it ; in the Acalyptratte, on the other 

 hand, the squama is so reduced in size that the halter is not 

 concealed when the insect is looked at from above. The 

 Muscidje Acalyptrata? include a very large number of small flies, 

 in which there is a great diversity of habits, especially in the 

 larval state, though the majority of the perfect insects resemble 

 the Common House-fly more or less closely in outward form, 

 though not necessarily in colour or markings. The group is split 

 up into a number of sub-divisions, which are regarded by some 

 writers as sub-families, while others assign to them at all events 

 nominal family rank. The Muscidee Calyptratse are generally 

 speaking flies of larger size and stouter build than the Acalyptratse. 

 The group is divided into a smaller number of sub-divisions than 

 the Acalyptrata;, and in its widest sense (= Muscaria Schizo- 

 metopa, of Brauer and von Bergenstamm), includes the nominal 

 families Tachinidse (bristly flies, the larvae of which are parasitic 

 in caterpillars and certain other insects), Dexidte, Sarcophagidiii 

 (marbled grey Flesh-flies), Muscidse (House-flies and their blood- 

 sucking allies belonging to the genera Stomoxys, Haematobia, 

 Lyperosia and Glcssina, Blue-bottles, Green-bottles, etc.), (Estridte 

 (Bot- and Warble-flies), and Anthomyidse (non-bristly Muscida;, 

 in which the first posterior cell of the wing is wide open). 



While there can be no doubt that it is impossible to find 

 hard and fast characters, wliich would warrant the maintenance 

 of the independence of the six so-called families that have just 

 been enumerated, there is fortunately no occasion to enter here 

 into the vexed question of Muscid taxonomy, which has engaged 

 the attention of various well-known dipterists during the last 

 few years. As has already been pointed out by the late F. M. van 

 der Wulp,* the genus Glossina was placed by its founder, Wiede- 

 mann, in the immediate neighbourhood of Stomoxys, Geoff., and 

 if we add to the group Heematohia, Rob.-Desv., Lyperosin, Bond., 



* " Tijdschrift voor Entomologie," xxvii. (1881), p. 114. 



