MADEIRAN GROUP. 261 



sensibly more oblique), and by the fact of the subvertical plait 

 of its aperture having a tendency to become more strictly tooth - 

 like (or abruptly terminated behind). It is true that the state 

 6 /3.' of the tornatellina has that callosity more dentiform than 

 the state ' a.,' and that it consequently makes an approach in 

 that respect to the mitriformis ; and it is equally certain that 

 the Madeiran individuals of the latter have the same plait more 

 narrow and linear than those from the other islands ; but I have 

 merely to remark that, in all instances, where one specific fea- 

 ture seems to fail, the others (as though to guard against con- 

 fusion) are expressed ; and I arrive therefore at the original 

 conclusion (which was adopted by Mr. Lowe) that the two shells 

 are more safely to be treated as specifically distinct. 



In certain ravines of Madeira proper (as, for instance, the 

 Eibeira de Sta. Luzia) the L. mitriformis is tolerably abundant, 

 for the most part amongst the detritus on the ledges (and at 

 base) of the lofty perpendicular rocks ; and on the three Desertas 

 I have myself taken it, in common with Mr. Lowe and others, 

 in considerable profusion. In the examples from those islands 

 the subvertical plait is unusually prominent and tooth-like, and 

 the species may consequently be said to attain there its maxi- 

 mum,, or normal phasis. The individuals from the Flat De- 

 serta (or Ilheo Chao) are rather pallid in hue, whilst those from 

 the Southern island (or Bugio) are comparatively dark and 

 highly coloured. 



In Porto Santo the L. mitriformis appears to be extremely 

 scarce. Indeed its existence there at all is vouched for by 

 merely a single dead example which was found by Mr. Lowe, in 

 1828, on the Pico Branco. That the latter however is truly 

 identical with the mitriformis (and not with the tornatellina) 

 I am able to assert (apart from the assurance of Mr. Lowe) by 

 actual observation, the example alluded to, in every respect 

 characteristic of the mitriformis, being now before me. 



The L. mitriformis is common in a subfossil state on the 

 Southern Deserta, where I have myself met with it in the muddy 

 deposits on the extreme summit of that almost inaccessible 

 island ; but it has not, I believe, been observed in the calcareous 

 beds either of Madeira proper or Porto Santo. 



Lovea producta, 



Achatina producta, Lowe, Ann. Nat. Hist. ix. 120 (1852) 

 Pfeiff., Mon. Hel. iii. 505 (1853) 



55 Lowe, Proc. Zool. Soc. Lond. 202 



(1854) 



Glandina producta, Alb., Mai. Mad. 60 (1854) 



