352 Bibliographical Notices. 



period when the whole of these islands were portions (and perhaps 

 very elevated ones) of a vast continuous land. 



" In the details of their trophi the genera of this section of the 

 Eucerata are so nearly similar, that we must not look, even in other- 

 wise anomalous forms, for any very striking irregularities there. 

 And yet the mouth is not altogether uncharacterized in Deucalion, 

 since its laterally-rounded upper lip, long and acuminated palpi (the 

 basal joint of which is broadly sinuated externally, as in Blabinotus), 

 together with its unusually produced and deeply bilobecl ligula, at 

 once remove it from Dorcadion, — from which moreover its largely 

 developed and exceedingly uneven prothorax (a hinder zone of which 

 is suddenly constricted, as though by a wide and tightened belt, and 

 is ribbed with transverse plaits), added to its curiously pitted and 

 tubercular elytra, will still further serve to separate it. In some 

 respects perhaps it is more akin to Parmena than to Dorcadion : 

 nevertheless its comparative^ gigantic size, and the contracted, pli- 

 cate, posterior band of its (otherwise) greatly wrinkled prothorax, 

 apart from the above-mentioned peculiarity of its elytral sculpture 

 (one of the most remarkable features which it possesses), and its 

 freedom from the dense elongated pile which is more or less evident 

 in all the members of the former, will equally distinguish it from 

 that group also. 



"Amongst other singularities, a tendency (which I have likewise 

 observed, occasionally, in the Morimi) to have one of their elytra a 

 little shorter than the other is strongly indicated in the Deucaliones. 

 Thus, of my two examples of the D. Desertarum one is very de- 

 cidedly so constituted ; and, out of eight of the D. oceanicum it is 

 traceable in no less than three. Like many of their allies in this 

 department of the Longicorns, they are gifted with the capability of 

 making a grating or hissing noise, — the modus operandi in producing 

 which (since I have not been able to meet with any explanation of it 

 altogether satisfactory) I have taken some pains to investigate. The 

 solution given by Mr. Westwood, in his admirable ' Introduction to 

 the Modern Classification of Insects' (vol. i. p. 3i)6), would seem to 

 come nearest to the truth, but still it does not quite apply to the 

 species under consideration, — which are moulded, thus far, on one 

 and the same principle. Mr. Westwood states that the sound is 

 generated by the friction of a polished portion of the scutellvm 

 against the edge of the prothoracic cavity. In Deucalion, Parmena 

 and Dorcadion, however, there is a narrow space, in the shape of an 

 isosceles triangle (the apex being turned towards the scutellum), 

 which occupies nearly the entire length of the mesonotum, and 

 which, from its brightness, appears at first sight to be perfectly 

 smooth. When viewed however beneath the microscope, this longi- 

 tudinal area is seen to be composed of very fine, transverse, parallel 

 and acute ridges, closely set together after the manner of a file : and 

 it is by depressing and raising the prothorax (an act which alternately 

 exposes and re-covers the upper region of the extremely cylindrical 

 mesothorax) that its under side is brought to play against this inner 

 dorsal file,— by which process the stridulation is effected. In order 



