502 II'STACEA ATLANT1CA. 



Habitat Portum .Sanctum ; in montibua excelsioribus, vel 

 inter Hellenes in rupinm fissuris vel plant is adherens, vulgaris. 



This brightly fasciated and elegant little Helix appears to 

 he peculiar to Porto Santo, 1 where it is common on most of the 

 higher peaks (particularly towards their summits), — occurring 

 principally among lichen, or adhering to the stems of plants, 

 within the fissures, and upon the ledges, of the rocks. In such 

 situations it has been met with abundantly, by Mr. Lowe, 

 myself, and others, on the Pico do Facho, the Pico do Castello, 

 the Pico Juliana, the Pico Branco, the Pico d'Anna Ferreira, &c. ; 

 from several of which it has subsequently been received by the 

 Baron Paiva. 



The H. Michaudi is a solid and rather globosely-conical, or 

 sub-trochiform, little species; and its surface (which is shining, 

 and somewhat distinctly striated with the irregular, oblique, 

 transverse lines of growth) is more or less white, but beautifully 

 ornamented with dark purplish-brown bands or fascia?, — two of 

 which are on the (slightly flattened) underside of the shell, and 

 become gradually lost sight of within the aperture, whilst a third 

 one is placed above the (obtuse and ill-defined) keel, running 

 along the centre of the volutions, uninterruptedly, to nearly the 

 apex. Its perforation is extremely minute, and almost entirely 

 concealed by the reflexed columellary edge of the peristome. 



Helix calva. 



Helix calva, Lowe, Cambr. Phil. 8. Trans, iv. 49. t. 5. f. 26 

 (1831) 

 „ „ Pfeiff., Mon. Hel. i. 289 (1848) 

 „ „ Lowe, Proc. Zool. Soc. Lond. 183 (1854) 

 „ „ Alb., Mai. Mad. 42. t. 11. f. 1-4 (1854) 

 „ „ Paiva, Mon. Moll. Mad. 37 (1867) 



Habitat Maderam ; sub lapidibus in graminosis montosis 

 excelsioribus degens. Semifossilis ad Canical copiose reperitur. 



The situation of the present Helix, in a natural arrangement, 

 is rather difficult to point out. In some respects it has a little 

 in common with the bifrons, Lowe,and the stephanopkora, Desh. ; 

 yet its minute and almost concealed umbilicus, in conjunction 

 with its margined peristome, will of themselves remove it from 

 the section Janulus, — and indeed, as it seems to me, from the 

 whole of the Patulas. By Mr. Lowe it was placed alongside the 

 H. obserata, in his section Rimula, but I scarcely think that 

 even that position is a more suitable one ; and on the whole I 

 am inclined to the Leminiscias as not altogether incapable o 



1 The IT. Michaudi is stated by Deshayes to occur in Teneriffe ; but that i s 

 clearly an error. 



