MADEIRAN GROUP. 195 



The sculpture of the //. coronata, although sufficiently ela- 

 borate, is somewhat less complex than that of either the //. del- 

 phinuloides or of the following four species. The keel, however, 

 is perhaps more pronounced than in any of them, — consisting 

 as it does, of a single, prominent, compressed, thread-like line, 

 simple (or undentate) ; but there is a series of large, greatly 

 raised, subconfluent nodules (or, in reality, oblique, centrally- 

 elevated ribs), forming a kind of chain, in the middle of each 

 volution on the upper side, which gradually becomes evanes- 

 cent as it approaches the nucleus, — occasioning the anterior 

 and posterior zones of each whorl to be as it were sunk (along 

 with the suture) into a groove, aud causing the keel of the 

 ultimate volution to be more shaped-out and prominent than it 

 would otherwise have been.' These abbreviated, tubercle- 

 sliaped ribs are continued on the under side (i.e. beneath the 

 keel), in the form of waved or imdulating concentric ridges, up 

 to the umbilicus, and even within it ; and between them very 

 minute spired superficial lines (or line-like markings) can just 

 be traced beneath a high magnifying power, — as though to 

 proclaim its affinity with the other, immediately allied forms- 

 Helix coronula. 



Helix coi'onula, Loive, Ann. Nat. Hist. ix. (1852) 

 „ „ Pfeiff., Mon. Hel. iii. 146 (1853) 



„ „ Loive, Proc. Zool. Soc. Lond. 194 (1854) 



„ „ ^^6., ifaL 71/at^. 81. t. 17. f. 5-7 (1854) 



„ „ (pars), Paiva, Mon. Moll. Mad. 63 (1867) 



Habitat Desertam Australem, semifossilis ; recens hactenus 

 baud inventa. 



The H. coronula was, I believe, first detected by Mr. 

 Leacock, in a subfossil condition, on the extreme summit of the 

 Southern Deserta (or Bugio), — a locality in which it was sub- 

 sequently met with, in abundance, by Mr. Lowe and myself, in 

 June of 1855 ; and it has since been obtained from the same 

 spot by the Baron Paiva. It is wrongly said by the latter to 

 have been found by Senhor J. M. Moniz, in a recent state, on 

 the Deserta Grande,— the species which was discovered by 

 Moniz being in reality altogether distinct,^ 



' The somewhat angular termiiMtion behind of this central chain-like pro- 

 jection of the lower whorls, which (by creating a depression, or groove, be- 

 neath it) causes the true keel to be strongly shaped-out, was mistaken by 

 Mr. Lowe (both in the present sj^ecies and in the //. coromda) for a second or 

 ' upper ' keel ; but a very slight examination will shew that it has, in reality, 

 nothing to do with the keel (properly so called) at all. 



^ Apart from his mistake concerning the //. Grabhami (pointed out below), 

 the Baron Paiva has strangely mixed up not only the characters but also the 



o 2 



