40 INSECTA MADERENSIA. 



the smaller members of the group. After a careful exammation, however, of their 

 oi-al organs, I can perceive nothing in structiu-e which intlieates the slightest 

 aljerration from the normal state ; and it is probable therefore that there may be 

 many specific gradations yet undiscovered in the mountains of central Eiu'ope, 

 wliich will unite the comparatively gigantic individuals of the south viixh. the 

 minute ones of northern regions. Some such steps indeed do actually occiu" in 

 the SavIss Alps, where I have taken, at a high altitude near the head of the 

 St. Gothard Pass, species (the A. sjiadicens, Dej., for instance, and the ^. alpestris, 

 Heer) having much the habits and outline of our present type, but inferior as 

 regards size. 



The Ai'gutors of Madeira, although not positively peculiar to the upland por- 

 tions of the island, are more particularly abundant between the limits of from 

 2000 to 4000 feet above the sea. On the southern side indeed they seldom make 

 their appearance below 1500 feet, although in the north, where the climate is con- 

 siderably colder, I have observed occasional specimens, dui'ing the winter months, 

 even on the level of the shore. In both instances however they begin to diminish 

 in numbers above 4000 feet, and at 5000 they have usually ceased. The sylvan 

 district in fact, properly so called, may be said to be tlieir range ; a definition how- 

 ever which, while it is actually true as regards altitude, is only partially so as 

 regards position, — since, in addition to their normal habitat, beneath stones, logs 

 of wood, and fallen leaves, Avithin the forest regions, they do also occiu* on the 

 grassy slopes and moist cloudy plains of the ojien covmtry. Up to the present 

 period I have not remarked a single Argutor in any of the other islands of the 

 group, from which indeed it is far from imjiossible that the genus may have 

 partially at any rate, if not entu-ely, disappeared since the destruction of the ancient* 

 timber, which is recorded, at least in Porto Santo*, to have been once luxTiriant. 



28. Argntor robustus, Woll. 

 A. robustus nigro-piceus subconvexus, prothorace quadrato, elytris profunde striatis singulo punctis 

 duobus minutissimis imprcsso, antennis pedibusque rufo-piceis. 

 Mas, nitidus, elytris parallelis ; tibiis intermediis curvatis ante apicem intus valde ampliato-distortis, 



posticis subrectis ad apicem dilatatis. 

 Fcem. subopacus, elytris ovatis ; tibiis posterioribiis simplicibus. 

 Long. Corp. liu. 5:^-6j. 



Habitat per regioncm Madera; sylvaticam, sub lapidibus truncisque arborum prolapsis, pi-resertirn a 

 .2000' usque ad 5000' s. m., toto auno frequens. 



A. robust, dark piccous, and a little convex. Protlwrax large, quadrate, with a slight dorsal channel, 

 and with a distinct subpuuctatc fovea on cither side at the base. Elytra deejily striated, the 



* Cf. Hktaria Insulana das Wios a Portugal Sugeytas no Oceano occidental. Composita par Antonio 

 CordvTo da Compagnia do Jcsu : Lisboa, 1717. 



