242 TEST ACE A ATLANTIC A. 



more closely set together and more flexuose, its surface is more 

 opake, and its colour is of a uniform dark brown. Its mode 

 of life too is not the same, it being found almost exclu- 

 sively under the dead leaves of the Semperviva which stud the 

 faces of the rocks in Madeira proper at low and intermediate 

 altitudes ; though it is now and then to be met with (as at 

 Canical), sparingly, even beneath stones. In this peculiarity of 

 its habitat it would seem, it is true, to have something in com- 

 mon with the ' status 7. obesiuscula ' of the C. deltostoma ; 

 nevertheless the latter is exceptional, as regards its modus vi- 

 vendi, for that species, the C. deltostoma (in its numerous 

 phases) being nearly always found adhering to stones, whether 

 about houses and walls, or in dry and exposed spots near the 

 coast. 



Genus 12. BALEA, Pridx. 



Balea perversa, 



Turbo perversus, Linn., Fna. Suec. No. 2172 (1761) 

 Balea perversa, Pfeiff., Mon. Hel. ii. 387 (1848) 



Lowe, Proc. ZooL Soc. Loud. 215 (1854) 



Alb., Mai. Mad. 69. t. 16. f. 15, 16 (1854) 



Morel, Hist. Nat. des Acor. 206 (1860) 



Paiva, Mon. Moll. Mad. 140 (1867) 



Watson, Journ. de Conch. 223 (1876) 



Habitat Portum Sanctum ; in summo ipsissimo mentis 

 ' Pico de Facho ' dicti, a meipso, tempore vernali 1 848, in ru- 

 pium fissuris basalticarum, parce lecta. 



The common European B. perversa was detected by myself, 

 during the spring of 1848, in Porto Santo, namely within fis- 

 sures of the exposed, basaltic, almost inaccessible, weather-beaten 

 rocks on the northern (and very precipitous) side of the extreme 

 summit of the Pico de Facho (about 1665 feet above the sea) ; 

 a locality in which I again met with it in April 1859. And it 

 has subsequently been obtained by the Baron Paiva, though 

 very sparingly, from the same spot, which, so far as I am 

 aware, represents its only ascertained habitat throughout the 

 Madeiran, Canarian, and Cape Verde archipelagos. 1 It appears 

 however to exist rather abundantly in the Azores. 



1 The Baron Paiva states that it occurs also on the summit of the Pico 

 Branco ; but as his Porto-Santan material was not obtained by himself, I 

 think that that particular habitat (although by no means an improbable one) 

 requires further corroboration. 



