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XI. An Appendix or Supplement to a Treatise on the GBstri and Cnterebne of 

 various Animals. By Bracv Clark, F.L.S., Corresponding Member of the 

 Royal Institute of France, 8$c. 



Read April 6th and 20th, 1841. 



1HE first memoir published by me on this subject was written in the 

 year 1/96, and printed in the Linnean Transactions for that year, vol. iii. 

 p. 289, which memoir, considerably enlarged, and forming a separate pub- 

 lication, was republished by me in the year lHlo, with a supplement added 

 the year following, containing further remarks and discoveries respecting this 

 singular race of insects, to which I now beg leave to add a second appendix 

 in the present communication. A great deal of new matter having sprung 

 up on these subjects in the course of the years which have elapsed since I 

 first wrote, mixed also pretty plentifully with error and confusion, (at least 

 such I apprehend to have been the case,) I propose to review it in this essay, 

 leaving the justice and propriety of my conclusions for the consideration and 

 decision of others. 



Not having encouragement enough for the republication of my above-men- 

 tioned work on these subjects, I am desirous by this memoir to make some 

 additions, and also to correct some passages of that publication, in order to 

 supply materials for any future edition of it that may at a future day possibly 

 be undertaken by myself or others. 



In the commencing or historical part of my work, at page 5, after the word 

 "conjecture," I should desire to have inserted the following notice, viz. " That 

 the fly alluded to by Moses in the above passage, and which is said by him 

 f to hiss and make a noise,' could, I suspect, have been no other than the 

 (Estrus Bonis of our enumeration ; and this hissing noise, so described by the 

 inspired writer, would greatly tend to confirm the truth of Virgil's elegant 

 description of the same thing, of its making a shrill sound or susurrus whilst 



vol. xix. M 



