200 TESTACEA ATLANTICA. 



The //. Monizicma lias the anterior zone of its whorls less 

 horizontal than in the H. coronula, but somewhat less oblique 

 (or tilted) than in the tiaretta ; and the abbreviated ribs, which 

 radiate from the suture over that anterior zone (particularly on 

 the ultimate volution, for on the penultimate one they are 

 'nearly obsolete), are much less elevated than in the former, and 

 a little less so than in the latter. The string-like keel is tole- 

 rably raised, arid irregularly subdentate ; and as there are no 

 spiral lines immediately beneath it, it is more isolated, and 

 therefore more conspicuous (even whilst less prominent) than in 

 the H. coronula. 



Helix tiarella. 



Helix tiarella, IF. et B., Aim. des Sc. Nat. 28. Syn. 31 G 



(1833) 

 55 55 dVrb., in W. et B. Hist. 62. t. 1. f. 26-28 



(1831) 

 „ „ Pfeiff., Mon. Hel. i. 191 (1848) 



?, 5, Loive, Proc. Zool. Soc. Lond. 194 (1854) 



„ „ Alb., Mai. Mad. 81. t. 17. f. 3, 4 (1854) 



„ „ Paiva, Mon. Moll. Mad. 62 (1867) 



„ „ Mouss., Faun. Mai. des Can. 58 (1872) 



Habitat Maderam ; ad rupes prseruptas maritimas, praBcipue 

 borealem versus insulae, hinc inde degens. Semifossilis prope 

 Canical copiosissime occurrit. 



The H. tiarella, which seems to be peculiar to Madeira proper, 

 was until 1855 supposed to be extinct, — it being extremely 

 abundant, in a subfossilized state, in the calcareous beds near 

 Canical ; but during July of that year it was first detected in a 

 recent condition by myself, and afterwards by Mr. Lowe, along 

 the sea-cliff road between the mouth of the Eibeira de Janella 

 and Porto Moniz, — where we succeeded ultimately in obtaining 

 about forty examples. It would appear however to be pretty 

 general along the whole line of the northern coast ; for later on in 

 the summer we again met with it between Seissal and Sao 

 Vicente, as well as at the Passa d'Areia (to the eastward of the 

 Sao Vicente ravine), where we secured at least 120 specimens, — 

 not only in the loose rubble at the sides of the road (where many 

 of them were dead), but also sticking (alive) on to the bare rocks, 

 — and, in a similar situation, at the Entrorza Pass, between 

 Ponta Delgada and Sta. Anna. 1 



1 This eminently Madeiran shell was described originally by Webb as 

 Ciinarian, on the strength of some specimens which had been obtained, along 

 with others of the If. tceniata (an equally distinctive Madeiran form), by 

 M. Terver, of Lyons, from a bag of dried Orchil, the precise origin of which 

 was confessedly unknown ! But there can be no doubt whatever that it was from 

 Madeyra, and not the Canaries, that the consignment of Itoccella had been 



