196 TESTACEA ATLANT1CA. 



The H. coronula (which is a little larger than the coronata, 

 Desh., measuring fully 3 lines, or a trifle more, across its 

 broadest part) is a round, depressed, and somewhat lozenge- 

 shaped shell, the anterior half of each volution, although sculp- 

 tured with coarse abbreviated radiating ribs, being horizontally 

 flattened. This horizontality of the anterior zone of each whorl 

 causes the line of transverse radiating ribs (which are abruptly 

 terminated behind) to shape out a kind of medial dentate keel 

 which is traceable up the spire, and which is very prominent on 

 the basal volution. Nevertheless it is not the true keel, which 

 latter is represented by a string-like, irregularly-dentate dorsal 

 line beloiv this great central ridge-like prominence, and which 

 is visible well-nigh up to the nucleus, in the shape of a jagged 

 or lacerated narrow lamella almost overlapping the suture. The 

 umbilicus of the H. coronula is wide, open, and spiral ; and 

 the entire basal region (including the umbilical wall) is most 

 beautifully and sharply sculptured with large spiral costse, 

 which are crossed, or decussated, by less elevated transverse 

 radiating ones. The aperture (which is constricted behind) is 

 considerably larger and less triangular than that of the Porto- 

 Santan H. coronata, and (as in the H. Grabhami, Moniziana, 

 and tiarella) destitute of an internal tooth. 



Helix Grabhami, n. sp. 



T. fulvo-lactea, latissime et perspective umbilicata, sub- 

 depresso-trochiformis, solidula, opaca, bicarinata, subtus spira- 

 liter costata et obsoletius transversim decussata ; spira subcon- 

 vexa ; anfractibus 7-7-J, antice costis magnis obtusissimis trans- 

 versis remotis radiantibus subalbidis, a sutura usque ad (aut 

 ultra) medium continuatis et ibidem abrupte terminatis (cari- 

 nam superiorem undulatam exstantem efficientibus), elegant- 

 issime instructis, carina propria distincta, sed vix dentata aut 

 lacerata, fere ad nucleum (ad suturam applicata) conspicua ; 

 umbilico magno, aperto, pervio, profundo ; apertura angulatim 



habitats ot this Helix and his nearly allied one taken (in a living condition) 

 in the east of Madeira proper, and which he described ultimately under the 

 name of H. Moniziana. This latter was regarded by Mr. Lowe (evidently 

 without much consideration) as the recent state of the South- Desertan sub- 

 fossil H. coronula, and as such it was published by him in 1862 ; and it is 

 evident that the Baron wrote his diagnosis of the caronula (or had it written 

 for him) on the strength of this conclusion of Mr. Lowe, for his ' var. a. 

 minor ... ad excelsos montes septentrionales insulse Maderag, rarissima, ad 

 herbarum radices fere sepulta,' although wrong in its diagnostic details, is 

 only explicable on that hypothesis. Finding afterwards however that the 

 Madeiran shell was not really conspecific with the Desertan one, he seems to 

 have described it under the title of H. Moniziana, but at the same time to 

 have omitted to strike out of his original diagnosis the Madeiran habitat. 

 Thus a degree of confusion has been created unnecessarily which is altogether 

 quite unpardonable. 



