84 TEST ACE A ATLAXTICA. 



and more numerous volutions, and in the coarser, fewer, and 

 more elevated cost^e (or folds) of its upper surface. 



Indeed the present Patula (so far as I am able to judge 

 fi-oni colourless and subfossilized examples) so nearly resembles 

 the ^ladeirau P. Guerineaaa that it might well-nigh be sup- 

 posed, at first sight, to represent but the quondam phasis of 

 that species. ^Maen accurately looked at, however, it will be 

 seen to possess a few difi'erential characters of its own which 

 will suffice to stamp it as a perhaps truly distinct, though 

 proximate, member of the same local assemblage. Thus it is 

 not only a little less flattened both above and below (the spire 

 being just appreciably less depressed, and the under portion of 

 the basal whorl conspicuously broader, convexer, and more de- 

 veloped), but its umbilicus is not quite so wide at the com- 

 mencement, its keel is les?; pronounced (or somewhat more 

 obtuse), and the costce of its upper surface are not only still 

 n.ore elevated and regular, but likewise appreciably less ob- 

 lique, — being more at right angles to the suture. \Miat its 

 colour may be, when in a recent condition, I have no means of 

 deciding. 



Patula Guerineana. 



Helix G-uerineana, Loice, Ann. Xat. Hist. ix. 115 (1852) 

 „ semiplicata, Pfeif., Mai. Bldtt. 6S {1852) 

 „ „ Id.,'\}Ion. Hel. iii. 114 (1853) 



„ Guerineana, Loa-e, Proc. Zool. Sac. Loud. 176 (1854) 

 „ semiplicata, Alb., Mai. Mad. 1 9. t. 2. f. 1 1-1 4 (1854) 

 „ „ Paiva, Mon. Moll. Mad. 80 (1867) 



H(d>itat Maderam; in sylvaticis intermediis rarior, sub 

 foliis marcidis necnon in humidis latens. 



This is one of the most elegant of the Madeiran Land- 

 Shells, — its flattened, discoidal contour, added to its enormous 

 vunbilicus, its highly polished (and obliquely, though very 

 ohseurely, subfasciated ) under-region, and the beautifully varie- 

 gated hue of its coarsely costate volutions (which seem to be 

 striped \sith alternate, but unequal, transverse bands of a lively 

 reddish-brown and of a dirty whitish-yellow) gi^^Ilg it an 

 appearance which it is impossible to mistake. Until lately it 

 has been regarded as the Madeiran representative of the 

 common Em-opean P. rotundata, Miill. ; but, as already shown, 

 it belongs to a rather ditferent type, — characterised by its more 

 numerous, narrower, and strongly costate whorls, by its brightly 

 polished, nearly unsculptured inferior portion, and by its still 

 larger umbilicus. And, apart fi-om these points, it is more de- 

 pressed, and (on the average) a trifle larger, than the P. rotiin- 

 da.ta, and its keel is sharper. Added to which, the latter 



