280 TEST ACE A ATLANTICA. 



loppcd-off, or decollated, spire of the adult shell) is not uncom- 

 mon below high-water mark in Madeira proper, beneath large 

 stones washed by the tide, — where it was first detected by Mr. 

 Lowe on the northern shore of the Ponta de Sao Lourenco. As 

 in higher latitudes, it assumes two tolerably distinct forms, — 

 one of them (which appears in Madeira to be normal) having 

 the volutions powerfully ribbed with elevated costoe, and the 

 other (/3. laevigata) being more shining, and with the costa) 

 more or less obsolete, the only place in which there are usually 

 conspicuous traces of them being towards the anterior margin 

 of each whorl. In other respects the T. truncatubi is charac- 

 terized by its cylindrical outline but nevertheless tumid volu- 

 tions, as well as by its rather narrow aperture, its solid substance, 

 and its pallid hue. 



In its strongly costate state the T. truncatula is somewhat 

 abundant in certain spots along the shores of Madeira proper ; 

 but the ' /3. laevigata ' seems to be scarce, though it is cited by 

 the Baron Paiva as occurring at the Gorgulho near Funchal. 

 From the Great Salvage, however, the latter phasis was received 

 in considerable numbers by the Baron, whilst the former (or 

 ribbed) one was less common. 



The young shells of the Truncatellce differ so curiously from 

 the adult ones, in their more conical outline and unbroken apex, 

 that they have occasionally been described not only as a distinct 

 species, but as pertaining to even another genus. 



Truncatella Lowei. 



Truncatella Lowei, Shuttl., Bern. Mitth. 146 (1852) 



„ „ Mouss., Faun. Mai. des Can. 147 



(1872) 



Habitat Maderam ; a Dom. Bewicke semel lecta. 



A single example of this Truncatella (which occurs in the 

 Canarian archipelago, and which I myself met with at the 

 Salinas in the north of Lauzarote) was taken in Madeira by the 

 late Mr. Bewicke, and is now in my possession ; though I have 

 no memorandum as to its precise locality. I believe, however, 

 that it was found near Funchal. But I am far from satisfied 

 that the T. Lowei is more in reality than an extreme, and 

 almost unsculptured, phasis of the preceding species ; though at 

 the same time it differs from even the ' /3. laevigata ' in being 

 almost totally free from sculpture, — there being only the faintest 

 possible traces of a few little pits and abbreviated hair-like costse 

 on the front edge of the volutions. These latter, moreover, are 

 not quite so convex. 



The Madeiran specimen now before me differs from the 



