302 J\lr. W. Wcsclie's Notes im the valve of 



1901 the Oitalidic, Trypctida- and Loncliicida3 follow each 

 other, but the horny telescopic ovipositor of the females 

 and the remarkable development of the Muscid form of 

 the male genitaha show that the differences between the 

 three sections are only generic, and that they form one 

 natural family. This opinion is strengthened by the 

 character of the troplii, which is fairly constant through 

 the group. In the labiums of the Ortalids Scoptrra vibrans, 

 L., and rtero]hvcfria nifjnna, Mg., and the Trypetid 

 Acidia li/eJmidis, F., are similar chitinous paired processes, 

 which are peculiar and striking. This shows a very close 

 relationship, and proves that a classification which places 

 the two first insects in one family and the third in another, 

 cannot be a natural one. 



T/ie ovipositor. Three types are met with in Diptera, (A) 

 the telescopic or protrusile, (B) the non-telescopic, and (E) 

 the styliform. The telescopic may be subdivided into (C) 

 those with a framework of chitinous rods and (D) those 

 without. The B type is undoubtedly the oldest and seems 

 nearly universal in the Nematocera. A and B are both 

 represented in the Muscida?, but B is far oftener met with 

 in the Acalyptrates. C seems confined to the Muscida?, 

 but examples of D may be met with in a few Syrphidai, 

 and in the Dolichopodine, Phoridce and Chloropodae. In 

 some Phorida^ the ovipositor has a lever to extend it, 

 somewhat similar in shape to a process found in the non- 

 telescopic ovipositor of the Simulida% and whose homolouge 

 appears to exist in a different form in the Chironomyidie. 



E. The styliform is found in the peculiar organ of the 

 Pipuuculidai, but there are one or two aberrant forms such 

 as Phoo'ocera serriventris, Rnd., which I have come across 

 in the Muscidre, which might come under this head, but 

 are really parallel developments. The types may be 

 arranged in a Phylogenetic scheme placed in the order of 

 hypothetical evolution, beginning with the oldest. 



B. JVon-telescojnc. 



E. Non-tcIcscopic chitinised forms as in P'qmneutvs. 



D. Telescopic without rods other than a single lever. 



C (^). Telescopic with many rods* 



* There are contained in the abdomen, parts of the female 

 genitalia that strangely enough have characters. These are the 

 receptacula seminis ; they vary in number from one to four, have 

 sculj)turing on the cases, and may have characteristic shapes in certain 

 genera, as in ralloptem, but their diilerenees are mostly specific. 



