100 TEST ACE A ATLANTIC A. 



diagnosis from the type of the latter) were communicated by 

 Mr. Leacock and Senhor J. M. Moniz, about 15 years ago, as 

 having been taken on the ' Ilheo de Fora,' a little islet off the 

 eastern coast of Porto Santo, opposite to the Pico do Concelho 

 (of the mainland) which is the sole locality (so far as I am 

 aware) for the H. Wollastoni ; and others have since been 

 received from the same spot by the Baron Paiva. They have 

 consequently been placed aside, for a considerable period and 

 without further examination, as representing in all probability 

 a smaller phasis, or variety, of the H. Wollastoni, which in 

 most of their features they nearly resemble ; and it must be 

 admitted that the situation of their habitat namely a little 

 islet exactly facing the particular mountain in Porto Santo 

 which seems alone to harbour the H. Wollastoni would tend 

 to favour the idea of an ' insular modification ' of that species. 

 Still, when closely inspected, the distinctive characters appear 

 to me to be too important and numerous to render it safe to 

 treat the present Helix as a mere phasis of the last one ; and 

 although it is not absolutely impossible that in reality it may 

 be so, I will only remark that there would be a primd facie 

 inconsistency about admitting it as such, while at the same time 

 allowing the specific claims of the H. Lyelliana, as distinct 

 from the Bulveriana, or those of the Lowei and Bowdichiana, 

 as distinct from the portosanctana and punctulata. 



Judging from a long array of examples which are now 

 before me, the H. fcwensis differs from the H. Wollastoni in 

 being smaller, and more densely and roughly granulated, and 

 therefore more opake, in its spire being somewhat more raised, 

 the nucleus especially (which is more shining, lightly sculptured, 

 and rosy) being more prominent, in its aperture being a little 

 rounder (or less sharply angled at the keel), in its upper and 

 lower lips being joined across the body-volution by a more 

 thickened corneous process, and by its colour being considerably 

 darker, or of a more reddish marbled-brown. Indeed its colora- 

 tion is on a rather different pattern, the volutions not being 

 ever (even indistinctly) fasciated, but unequally suffused all 

 over with the obscurer tint; whilst the single band on the 

 underside is broad and completely lateral, extending to the 

 very edge of the keel, instead of being (when present at all) 

 narrow and removed to a certain distance from it. 



( Mitra, Alters.) 



Helix Webbiana. 



Helix Webbiana, Lowe, Cambr. Phil. S. Trans, iv. 44. t. 5. 

 f. 10 (1831) 



