166 TEST ACE A ATLANTIC A. 



exstanti acuta distincta, sed carina interiore magis obtuse 

 rotundata faciliusque recedente, interdum etiam obsoleta. 



Habitat Portum Sanctum ; in monte ' Pico d'Anna Ferreira ' 

 dicto sat copiose reperta. Necnon in statu semifossili (cum 

 exemplaribus recentibus vix omnino congruens) parcissime oc- 

 currit. 



This little Helix, which was obtained rather abundantly by 

 myself on the Pico d'Anna Ferreira in Porto Santo, and after- 

 wards by Mr. Lowe (who apparently did not recognise it as 

 specifically distinct), is closely allied to the hicarinata. Sow., 

 and the echhiulata, Lowe, — to both of which it stands in much 

 the same relation as the H. commixta does to the abjecta. 

 And in the comparative fineness of its sculpture it makes like- 

 wise somewhat of an approach to the H. oxytropis, — the foiu* 

 species (namely echinulata, bicarinata, Leacockiana, and oxy- 

 tropis) constituting, in conjunction with the echinoderma, 

 vermetiformis, and turricula, a very natural assemblage. 



In the fact of its volutions having an additional central keel 

 (which consequently appears to be doubled on the ultimate one) 

 the H. Leacochiana has more in common with the bicarinata 

 than it has with the echinulata ; nevertheless in the granula- 

 tions of its surface being both very much smaller and very 

 much less raised (as well as more densely packed together) it 

 recedes equally from them both. But its more appreciable 

 distinctive character consists in the peculiar shape of its volu- 

 tions, especially of the last one, which is more strictly tectiform 

 (or roof-shaped), as well as of a relatively somewhat wider 

 diameter, than in the cognate species, — the edge, or outer keel, 

 being very much more prominent, whilst the inner one is more 

 completely and obtusely rounded-ofF, and therefore recedes more 

 from the former than is the case in the H. bicarinata. These 

 various little features are so conspicuous, when once seen, that 

 it is impossible to confound the H. Leacockiana with any of 

 these immediate forms ; and it appears to me to have far 

 greater claims for specific separation than the bicarinata has 

 from the echinulata ; and indeed I cannot but think that it is 

 removed from them both quite as much as the (very much 

 larger) oxytropis is, though in a different manner. 



I possess two subfossil individuals, a trifle larger and some- 

 what less finely granulated than those now before me of the 

 H. Leacockiana, which I have little doubt (from their general 

 contour and proportions) represent the quondam analogue of 

 this species. 



I have had great pleasure in naming the present little 

 Helix after my old friend T. S. Leacock, Esq., — whose long 

 residence in Madeira, and whose continued and careful re- 



