732 Mr. Gilbert J. Arrow on 



on the coxae of tlie preceding pair of legs, the vibratory 

 edges of which are plucked by the finger-like processes. It 

 is remarkable that this much-raoditied remnant of a leg 

 reappears in the mature beetle as a perfectly-formed limb, 

 practically like the second pair, and having no other 

 function than that of progression, while the vocal appar- 

 atus appears in an entirely different form and position. 

 The fact of stridulatiun by the adult beetle seems to have 

 been first published by Dr. Leconte, but Professor Poulton 

 has kindly sent me a much earlier record found by him 

 amongst the hitherto unpublished notes of the traveller 

 Burchell, and dated Dec. 9Lh, 1826. This very careful 

 observer writes of species of Neleus and Veturius which he 

 found at Rio las Pedras, Cubatao, Brazil, and believed, no 

 doubt, to belong to a single species : — " On taking it in 

 the hand it makes a faint [sound] between a hissing 

 and a squeaking, like the Lami[e." The sound produced 

 by both larva and beetle is described by Dr. Ohaus as 

 very distinctly audible, but the means by which it is 

 produced in the latter have been the subject of several 

 different opinions. It has been most generally supposed 

 that the abdomen and elytra were the parts concerned, but 

 none of the regions pointed out as directly participating 

 show any real co-adaptation for such a function. There 

 is no doubt that the true explanation is that given by 

 Mr. G. F. Babb, of Massachusetts, in the " Entomological 

 News" for 1901. The purpose is achieved by the opposi- 

 tion of spinose areas upon the wings to spines upon a 

 pair of elevations towards the end of the abdomen, that 

 is, by means somewhat similar to those which I have 

 described in species of the genus Bolhoceras. The two 

 terminal segments of the abdomen are rigid above, but 

 the one preceding them is membranous and flexible, with 

 the exception of a much-thickened strip at its hinder 

 border. Connected with each end_^of this chitinized strip 

 there is a hard boss the surface of which has a velvety 

 appearance, which proves under the microscope to be due 

 to erect spines massed thickly together. These bosses 

 occupy almost the same position as the peculiar processes 

 which I have described in OchodcVus, although owing to 

 the long and narrow shape of the body they are nearer 

 together and more terminal and are covered by the wing?!. 

 Each of the latter lies closely against the flattened surface 

 of the wing-cover, and the hard angle formed at the 



