Transactions of the Liinnean Societt/. 585 



rect errors into which he supposes Mr. MacLeav to have fallen 

 in his memoir " On the Insect called Oistros by the Ancient 

 Greeks, and Asilus by the Romans," which was inserted in the 

 14th volume of the Linnean Transactions, and briefly analysed ia 

 the first volume of the Zoological Journal. In the substance of 

 Mr. B. Clark's paper there is, however, nothing which even tends 

 toJnvalidate the deductions of Mr. MacLeay; on the contrary, it 

 is adapted to confirm his leading position, so far at least as bare 

 assertion can confirm proofs almost amounting to positive. '' It 

 is more than probable, nay, almost certain," says Mr. Clark, 

 " that if Aristotle, ^Elian, or Pliny, described an insect — with a 

 trunk or proboscis, they knew nothing about the true CEstrus 

 Bovt's.^' That they did describe under the name of Oistros an 

 insect having a proboscis, was shewn by the quotations brought 

 forward by Mr. MacLeay from Aristotle, jElian, and yEschylus. 

 Of course then, even on Mr. B. Clark's own statement, the Oistros 

 of the ancient Greek writers was not the CEstrus of Linne, of 

 which, according to him, they knew nothing. Mr. MacLeay 

 proceeded further. Having shown what the Oistros of the ancients 

 was not, he endeavoured to ascertain what it was ; and as that 

 insect possessed not only a proboscis, but a very powerful one, 

 capable of piercing through the hides of cattle, and of sucking the 

 blood from beneath them, he regarded it as probably a Tabunus, 

 L., and from other circumstances, unnecessary to be mentioned 

 here, was induced to suspect strongly that it was some species of 

 the modern genus separated from that group, under the name of 

 Hcematopota. To all this Mr. B. Clark says nothing, except that 

 no Tabatius, Hcematopota, or certain other Dipterous Insects, 

 which he names, but to which no allusion was made by Mr. Mac 

 Leay, could produce those effects which are described by Virgil, 

 as resulting from the approach of his Oistros and Asilus. This, 

 however, is quite extraneous to the question discussed by Mr. Mac 

 Leay. That gentleman proposed to himself to ascertain as nearly 

 as possible the precise insect known at a given early period by 

 certain names ; and the enquiry as to the real cause of the effects 

 ascribed to it by the poets, formed no part of the object of his 

 investigation. Yet even in his incidental remark on the proba- 



