18 Mr. T. V. Wollaston on two new Plinthi. 
sity ; and I have since been assured by him that he has heard 
the music constantly in the A. dispar, nodiferus, terminalis, and 
ornatus ; and that “it was distinctly audible” in even the minute 
A. Wollastoni, which is the smallest of all the Madeiran Curcu- 
honide hitherto discovered. . 
But it is not in Acalles only that I have observed this anoma- 
lous proceeding. After having become familiar with it in the 
A. argillosus, 1 detected it likewise, before leaving Teneriffe, in 
a large and noble Plinthus, which seems to be peculiar to the 
Canaries. In that insect, however, the music was scarcely so 
loud, in proportion to the size of the creature, as was that of the 
Acalles; nevertheless the stridulating instrument is, perhaps, 
somewhat better defined. It is entirely the same, in position 
and general character, as the one which obtains in Acalles, ex- 
cept that the subopake portion of the inner tegument of the 
elytra (corresponding with the constricted apical region as seen 
from above) is, instead of being subreticulose, strictly file-like, 
being made up of a series of minute, closely-set, regular and 
parallel ridges, similar to those on the mesonotum of the Longi- 
corns. I subjoin the following diagnosis of this magnificent 
Plinthus :— 
Plinthus musicus, n. sp. 
P. squamis fuscis dense nebulosus et setulis demissis pallidioribus 
parce irroratus ; rostro graciliusculo, ad basin (ante oculos) leviter 
rotundato-ampliato; prothorace inzequali, carinato, parce punc- 
tato (punctis maximis) ; elytris ante apicem lateraliter constrictis, 
utroque ad apicem ipsum leviter acuminato (excavationem parvam 
communem efficiente), squamis albidioribus circa humeros et api- 
cem, necnon aliis maculam parvam rotundatam discalem et fasciam 
fractam transversam postmediam efficientibus (omnibus plus minus 
obsoletis), ornatis, profunde striato-punctatis, interstitiis alternis 
leviter elevatis ; femoribus dentatis. 
Long. corp. lin. 6-63. 
Habitat editiora sylvatica Teneriffee, sub lapidibus, passim. 
A distinct and beautiful Plinthus, which may be well known 
(when in a fresh and wnrubbed condition) by the paler scales 
about the sides of its prothorax, as well as about the humeral 
region and apex of its elytra,—which last have also a small — 
discal patch and a much broken postmedial fascia. It is closely 
allied to another and still rarer species, of which I likewise add 
a diagnosis,—this being perhaps the best place in which to do 
so, though I did not happen to observe any stridulating power 
in any of the few specimens which I have hitherto captured of 
it. In the P. musicus I not only observed it frequently, but I 
even effected the noise artificially by vibrating (though some- 
what clumsily) the terminal segment of the abdomen; but I 
