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- 

 lionida 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, I 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 insequali, 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. 6-6%. 



Habitat editiora sylvatica Teneriffse, sub lapidibus, passim. 



A distinct and beautiful Plinthus, which may be well known 

 (when in a fresh and unrubbed 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 



