456 W. WESCHE ON THE LIFE-HISTORY OF THE TACHINID FLY, 



• 



of such a condition. I have a note that the Anthomyid, Hylemyia 

 strigosa, F., brings forth living larvae, one at a time, but this is 

 doubtful, and is contradicted by Schiner, but there is no doubt 

 that Glossina palpalis, Des., has been found by Professor Minchin 

 to have a somewhat similar organisation * (Fig. 10). 



There is a Muscid fly in New Zealand which is reported to be 

 viviparous, the larvae being dropped on blankets ; besides this 

 I know of only two more genera (there are probably a great 

 number) in which the viviparous condition is found. Schiner 

 describes Sarcophaga and Onesia as being " vivipar." In the last 

 genus it is of some importance as a natural generic character,, 

 as the morphological characters appear to include the species in 

 Calliphora, with our well-known blow-fly, whereas it is placed by 

 Schiner close to Sarcophaga. 



In conclusion, there is one point which perhaps might have 

 been mentioned earlier ; it is that of a secondary sexual character 

 of many Tachinids. In Kobineau-Desvoidy's rather heterogeneous 

 genus of Nemoraea, which has been so much split up by later 

 systematists, it is stated that the fore tarsi of the females are 

 often dilated, while those of the males remain unaltered. f This 

 is also the case in Polidea, and strikingly so in many exotic 

 genera. I was at a loss for an explanation of this specialisation. 

 In many genera it is found as an exclusively male character, and 

 the reason for its existence is simple and obvious. But till I 

 came to consider the case of P. serriventris, which has perfectly 

 simple tarsi on the forelegs of both sexes, I was exceedingly 

 puzzled. But when we remember that it is only the females 

 that attack the Lepidopterous larvae, it is at once obvious that 

 the fore tarsi have become modified to contain the larger muscles, 

 necessary to enable the flies to maintain a firm hold of the cater- 

 pillars while ovipositing. 



1 would like to add two observations which have been made 

 since the above was in type. 



* Proc. Roy. Soc, vol. xiii. 76, 1905, p. 543. 

 f Lie Flugtv, vol. i. p. 447. 



