OF THE ANTENNAE OF INSECTS. 395 



Ne^Tport on the habits of insects, I think it may be concluded that the antenna! organs 

 are formed upon a plan in accordance with our present ideas of an auditory apparatus, 

 and ai'e therefore capable of hearing, and that : — 1st, they consist of a cell, sac, or cavity 

 filled with fluid, closed in from the air by a membrane analogous to that which closes 

 the foramen ovale in the higher animals ; 2nd, that this membrane is for the most part 

 thin and delicate, but often projects above the surface, in either a hemispherical, conical, 

 or canoe-shaped, or even hair-like form, or variously marked ; 3rdly, that the antennal 

 nerve gives off branches which come in contact with the inner wall of the sacs ; but whether 

 the nerve enters, or, as is most probable, ends in tlie small internally projecting papilla 

 which I have shown to exist in many of these sacs, it is very difficult to say. The principal 

 part of the nerve proceeds to these organs, the remaining portion passing to the muscles, 

 and to the roots of the hau's, at least to those of the larger sort. The distribution of the 

 nerve can be very beautifully seen in the antennaj of the Froncejts before mentioned, as 

 also in Odynerus. 



Another point, which might be mentioned as rather tending by inference to the con- 

 firmation of this opinion respecting the antennal organs, is that in the Shrimp and Craw- 

 fish among the Crustaceans (wliich have a sac at the base of the antenna, commonly 

 regaiKled as the auditory organ) there is no trace of any organs similar to those of the 

 Insecta ; the nerve simply supplies the hairs and muscles. 



More than a year after the reading of my former paper on this subject, one was read on 

 August 30, 1858, by M. Lespds, before the Academy of Sciences, Paris, reported upon satis* 

 factorily by a Committee, and subsequently published in the ' Annales des Sciences Na- 

 turelles :' Paris, 1858. The title of this paper was " The Auditory Apparatus of Insects." 

 Both the author and the reporters seem ignorant of what I had already done on this 

 subject, as, by not being aware of the value of bleaching the integument, M. Lespds 

 had very great difficulties to contend with, which would have been avoided had he 

 used that process, and moreover he would have escaped a great error. He had in con- 

 sequence to employ the most colourless species ; and the most minute of his researches 

 were upon the antenna of the Lamellicorns, Melolontha, Folyphylhts, &e., and he was 

 obliged to view the organs perpendicularly only. He certainly asserts the existence of 

 sacs behind the membranes, which he calls " tympanules," and gives a draA\'ing and 

 description of the ultimate branches of the antennal nerve proceeding to them. But he 

 states that the sac or cell (which he terms " cellule," or " iwche ") contains a rounded, 

 transparent, solid body attached to the inside of the membrane ; this body he calls an 

 " otolithe." Now, in all the numerous antennae which I have observed with good and 

 high powers, I have never seen this otolithe, the nearest approach to that body being the 

 small chain of solid gi-anules passing, in Tetrix, from the centre of the closing-in mem- 

 br^e to the back of the sac. But by following his directions for the observation of these 

 structures in Melolontha, by splitting open one lamella of the antenna and viewing the 

 wall from within, I have seen the very same appearance he descriljes, when viewing it 

 with low powers. However, the apparent otolithe is very soon resolved into its true 

 nature : for by using an ^-inch objective and high eye-piece, the appearance supposed to be 

 the otolithe is seen long before the rest of the sac ; and by adjusting the focus, the otolithe 



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