Mr. T. V. Wollaston on certain Musical Curculionide. 17 
and that, when the insect is alarmed, it is in a state of constant 
and most rapid vibration. Now, whilst the under surface of this 
abdominal apex is merely clothed with scales, the upper surface 
(or pygidium) is destitute of scales, but slightly rough, deeply 
punctured, and sefose ; and the inner portion of the elytra (cor- 
responding with the constricted, or suddenly-attenuated, apical 
region, as seen from above), against which the pygidium comes 
in contact at each of the pulsatory movements, is, to the naked 
eye, merely dull and subopake (instead of being glossy, like the 
rest of the inner tegument of the elytra); but when viewed be- 
neath the microscope, this duller portion is coarsely shagreened, 
or, more strictly, perhaps, minutely and very densely subreticu- 
late : and I conceive that it is by the play of the bristles of the 
pygidium against this subreticulated portion of the inner surface 
of the elytra (assisted, perhaps, by the setz at the apex of the 
dorsal apical segment, which comes in contact with the inner 
surface of the ventral apical segment, which is likewise reticulate) 
that the music is generated. 
In the gigantic Acalles Neptunus from the Salvages (an old 
specimen of which I have just destroyed, ia order to ascertain 
whether it also possesses a similar stridulating instrument), the 
reticulations of the inner surface of this constricted apical portion 
of the elytra are much more elongate, appearing, at first sight, 
almost like the ridges of the mesothoracic file of Deucalion; 
nevertheless, when viewed beneath a high magnifying power, 
they are perceived (no less than those of the A. argillosus) to be 
true reticulations, or meshes, being more or less irregular in 
their formation, and made up of obliquely-transverse, as well 
as longitudinal lines. I should therefore conclude, from the 
large size of the sect and the comparative coarseness of its 
subanal apparatus, that it is, in all probability, a species of great 
musical capabilities. 
Whether all the Acalles have this remarkable power, I will 
not undertake to pronounce; but so far as the numerous repre- 
sentatives from the Atlantic islands are concerned, I have but 
little hesitation, from the general appearance of the constricted 
apical region of their elytra, in believing that they have. And, 
indeed, this conjecture has been absolutely verified in five of the 
Madeiran ones by the direct and careful observations of Mr. 
Bewicke, from whom I have received some very interesting re- 
marks concerning them. On my arrival at Fupchal, from Tene- 
riffe, m June 1859, I exhibited my specimens (then in a lively 
state) of the A. argillosus to Mr. Bewicke, and requested him to 
listen attentively to the Madeiran species, whenever he chanced 
to meet with them, during the following summer, in order to 
ascertain whether or not they had a similar stridulating propen- 
Ann. & Mag. N. Hist. Ser.3. Vol. vi, 2 
