92 TEST ACE A ATLANTIC A. 



and that both are still living (the Loioei being all hut extinct, 

 whilst the portosanctana is universal), in conjunction with the 

 circumstance that there are no traces of genuine intermediate 

 links (either fossil or recent), would seem to imply, at any rate 

 to my mind, that the two ftu-ms were aboriginally distinct, but 

 that they have been slowly changing places as regards ascen- 

 dency. 



The H. portosanctana passes through many degrees of 

 colour and outline, — some examples being abruptly banded, 

 and others with the fasciae so greatly increased and suffused that 

 they appear at first sight to be well-nigh unicolorous ; whilst 

 many specimens have the spire comparatively elevated, and 

 others comparatively depressed. But there is one form (amongst 

 the numerous others, more or less slightly differing) which may 

 properly be noticed as more salient than the rest, but which does 

 not seem to have been sufficiently brought forward by Mr. Lowe. 

 I allude to the particular phasis which occm's more especially 

 (though intermingled with the ordinary type) on the liheo de 

 Cima, and which is (on the average) rather l&vger, flatter, and 

 thinner than is usually the case, with the umbilicus generally 

 wide and open, and with the surface for the most part darker 

 (the fascige being broad and sufused), as well as (when viewed 

 beneath a high magnifying power) more thickly and decidedly 

 subpunctulate. This aspect of the shell, which I think perhaps 

 is the only one which it is worth while to single out as a posi- 

 tive ' variety,' we may be permitted to record as the ' var. ^. 

 cimensis.'' 



When inspected under a powerful lens, the H. pjortosanc- 

 tana will generally be seen (in individuals which are fresh and 

 unrubbed) to be infinitesimally hispid, or pubescent. 



(§ Crijjjtaxis, Lowe.) 



Helix Vulcania. 



Helix vulcania, Loiue, Ann. Nat. Hist. (1852) 

 „ „ Pfeijf., Mon. Hel. iii. 147 (1853) 



55 5, Lowe, Proc. Zool. Soc. Lond. 168 (1854) 



„ „ (pars),yl^6.,J/a/.7lfad48.t. 13.f.4-6(1854) 



„ „ Paiva, Mon. Moll. Mad. 17 (1867) 



Habitat Desertam Eorealem, et Desertam Grrandem ; sub 

 lapidibus vulgaris. 



The H. portosanctana, the Vulcania (with its closely allied 

 H. leonina), and the undata may be regarded as strictly ' re- 

 presentative ' species, — the first being peculiarly Porto-Santan, 

 the second Desertan, and the third Madeiran ; yet it is impos- 

 sible to treat them practically as, in any degree, insular modi- 



