94 TEST ACE A ATLANTIC A. 



Vidcania obsolete, — causing the basal volution to be two-, in- 

 stead of three-fasciated ; and the upper band (just below the 

 suture) lias a greater or less tendency to be broken-up or inter- 

 rupted, — giving a somewhat dappled, or tessellated, appearance 

 to the anterior region of each whorl. The ground-colour of the 

 If. Vulcania is an olivaceous brown ; and the volutions are 

 obliquely striated with irregular, sub-undulating, more or less 

 confluent ribs, — imparting a malleated character to the whole. 



The examples of this shell from the Northern (or Flat) 

 Deserta may be looked upon as the most typical ones for the 

 species, and they are (on the average) a little more depressed 

 (and perhaps a trifle smaller) than those from the Deserta 

 Grande, the basal whorl being somewhat less inflated and with 

 a more evident tendency to have an obsolete keel ; and their 

 surface is rather more closely, and not quite so coarsely striate, 

 or so conspicuously malleated. The very slightly altered aspect 

 of the H. Vulcania from the Deserta Grande, or central island, 

 we may perhaps cite as the ' var. /3. desertce.' 



The H. Vulcania was first detected by Mr. Leacock, in 

 June, 1848; and it has subsequently been met with by Mr. 

 Lowe, myself, and others, in considerable profusion, on both of 

 the more northern Desertas. 



Helix leonina. 



Helix leonina, Lowe, Ann. Nat. Hist. ix. (1852) 

 „ Vulcania, var., Pfeijf., Mon. Hel. iii. 148 (1853) 

 leonina, Lowe, Proc. Zool. Soc. Lond. 168 (1854) 

 Vulcania, var. /3., Alb., Med. Mad. 48, t. 13. f. 1-3 



(1854) 

 „ leonina, Paiva, Mon. Moll. Mad. 18 (1867) 



Habitat Desertam Australem, vulgaris ; necnon etiam (var. 

 a. intermedia) Desertam Grandem, sed ibidem rarior. 



As already mentioned, this may perhaps represent but an 

 enlarged and local modification of the H. Vulcania ; neverthe- 

 less it certainly is not an insular one, inasmuch as it co-exists 

 with that species on the Deserta Grande ; and, whatever there- 

 fore be the true state of the case, I think that it will practically 

 be more convenient to cite it as distinct. 



The H. leonina is larger and more highly coloured than the 

 Vulcania, — its basal volution being more inflated, and with the 

 two bands (the anterior one of which has scarcely any tendency 

 to be broken-up or tessellated) more broadly developed ; its 

 surface is even still more coarsely malleated ; and its columella 

 is proportionately longer. 



It is on the Southern Deserta (or Bugio) that the II. leonina 



55 

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