103 TEST ACE A ATLANTIC A. 



surface 1 and smaller umbilicus, added to the sharper edge of its 

 ultimate volution and its more raised and continuous peri- 

 stome, will readily distinguish it from every phasis of that 

 variable species. Believing it far from unlikely, however, that 

 this particular subfossil Helix to which I am now calling 

 attention may be separated by some future monographer from 

 the oxytropis proper, I will briefly characterize it as follows : 



H. oxytropis, Lowe; var. ft. subcarinulata. — Major, spira 

 magis elevata, ad apicem paulo magis acuta, anfractibus in 

 medio obsolete subcarinulato. — Long, axis 2± lin. ; diam. 3^. 



(§ Turritella, Woll.) 



Helix cheiranthicola. 



Helix cheiranthicola, Lowe, Cambr. Phil. S. Trans, iv. 57. 



t. 6. f. 17 (1831) 

 „ „ Pfeiff., Mon. Hel. i. 212 (1848) 



„ „ Lowe,Proc. ZqoI. Soc. Lond. 187 (1 854) 



„ „ Alb., Mai. Mad. 37. t. 9. f. 14-16 



(1854) 

 „ „ (pars), Paiva, Mon. Moll. Mad. 48 



(1867) 

 var. mustelina, Lowe. 



Helix mustelina, Loive, Proc. Zool. Soc. Lond. 186 (1854) 

 „ cheiranthicola, ft. minor, Paiva, I. c. 49 (1867) 



Habitat Port um Sanctum, insulamque parvam adjacentem 

 ' Ilheo de Baixo ' dictam ; in montibus hinc inde vulgaris, cau- 

 libus Cheiranthi arbuscidoe, Lowe, saepissime adherens. Semi- 

 fossilis, et in Campo de Baixo et in Ilheo de Baixo, parce 

 reperitur. 



Owing doubtless to the great elevation of its spire, the H. 

 cheiranthicola was placed by Mr. Lowe and Dr. Albers (and, copy- 

 ing them, by the Baron Paiva) in the section Hystricella ; but 

 it seems to me to have quite as much in common (indeed even 

 more, in some respects) with the Discula type, and I think 

 therefore that we may safely regard it as exactly intermediate 

 between the two, — though belonging absolutely to neither of 

 them. The Hystricella group is so wonderfully well defined — 

 not only in the continuous, raised, circular peristome of its seve- 

 ral members, but likewise in its sculpture and the very great 

 peculiarity of its colouring — that it seems a pity to admit into 

 it a species like the present one, which is so thoroughly different 

 in the generality of its features ; whilst, at the same time, the 

 H. cheiranthicola is too high and turret-shaped to be properly 

 referred to the section Discula. 



The //. cheiranthicola occurs on certain of the loftier moun- 



