300 Mr. W. Wesch^'s Notes on the value of 



From tbis it can be seen tbat tbe presumption of close 

 relationsbip suggested by tbe mouth is contradicted by 

 the character of tbe male genitalia, and the venation only 

 proves a family relationsbip. But when the extraordinary 

 changes in the ovaries of the female of G. paljmJis, Des., 

 shown in Prof. E. A. Mincbin's paper,* Stonioxys remain- 

 ing normal, are taken into consideration, together with 

 many other points of structure external and internal, it 

 is clear tbat Glossina and Stomoa-ys are far removed from 

 each other. 



A comparison of the Muscid species bearing specialised 

 tropin, Dryinia, Stoinoxys, Hminatobia^ Lyi)erosa, Proscna, 

 Siphona, Glossina and Madyza (tbe details of the argu- 

 ment are too long to quote here), has led me to tbe 

 conclusion tbat these specialised moutbs, like those of the 

 genera already quoted, are cases of parallel development. 



The genital affinities between Tipula, Scatopse, the 

 Stratiomyid genera, Asilus, Dolichopus and tbe Empidse 

 are supported by a similarity which is also a peculiarity, 

 in tbe anatomy of the mouth. In families in which the 

 mandibles are aborted, they are embedded in tbe labium. 



(1) In the Tipulidcfi it can be demonstrated that they are 

 in the ventral side, as the lever on the dorsal side sends out 

 processes to wbich the palpi are attached, which shows 

 that they are tbe fused cardines and stipites of the 

 maxillse, 



(2) In Dolivhop^iS there is a marked thickening of the 

 mentum on tbe median line and a structure showing the 

 presence of atrophied or aborted organs. In the related 

 Aphrosyl'us raptor, Hal., tbe mentum is simple and 

 without this structure, but two chitinous blades can be 

 dissected out of tbe muscles underneath it. 



(3) In tbe Empidse, Stratiomyidse and ^catopse this 

 character of a thickening of the chitin of tbe mentum on 

 the median line is very marked. 



(4) In the Asilidas tbe mandibles are present, so the 

 character fails, but the presence in the head of a structure, 

 homologous with tbe pharyngeal pump in GuUx and 

 Tipula, connects it with the Empidse and Dolichopodidse, 

 and so establishes the value of tbe genitalia character in 

 all these instances. 



The second type of penis, that found in PtycJioptera 



* Report on t.lie anatomy of the Tsetse-fly {Glosiiina p^dpal's) 

 Proc. Roy. Soc, vol. 76 B, 1905. 



