CALL1PH0RA ERYTHROCEPHALA, MG. 287 



tribes, the Cyclorrapha and the Orthorrapha, descended from 

 related ancestors. 



We have now separated the group of families to which the 

 Blow-fly belongs from a number of the other families by a 

 character in the proboscis, and this is confirmed in a remarkable 

 manner by the character of the pupa-case. It therefore seems 

 highly probable that this character is a reliable one, and, as I 

 shall show, enables me to trace the pedigree of the Blow-fly 

 further back, to the point where it separates from the families 

 known as the Brachycera. I have already shown that in the 

 Leptidae two nearly related insects have two types of structure 

 on the ventral side of the proboscis, one (L. conspicita) with 

 lateral rods, and another (Chrysopilus) with a plate in which, 

 judging from appearances, these rods are embedded. I can also 

 show that in the nearly related Tabanidae many species are 

 without the mentum, as in T. bovinus, but it will be found 

 fully developed in Haematopota phcvialis, Li., and without any 

 sign of the thickening in the median line, owing to the insect 

 possessing fully developed mandibles (Fig. 10) \ in fact, in a 

 similar condition to that which is found in the Blow-fly.* This 

 fly is a well-known British species, and is, I believe, popularly 

 known in some districts as the " grey Clegg." I have little 

 doubt but that in this genus is found a form approximating to 

 the ancestral form of the Muscidae ; but the "branching off ,! 

 took place at a very remote period, before the Tabanidae lost the 

 labial palpi. 



The venation of the wings has, like the mouth, undergone 

 simplification, but confirms this hypothesis in a striking manner. 

 It must, however, be understood that the Blow-fly is itself one of 

 the later Muscids, for the older forms of venation are represented 

 in the Anthomyidae (Fig. 2, p. 288). 



* As a " control " observation an exotic Haematopota has been examined 

 (H. pertinent, Austen, from British Central Africa), and the mentum is 

 practically the same as that described above (Fig. 12). 



