^-^ . ^ ^TJSSTACEA ATLANTICA. 



reflexed, and the central part of its underside is of a paler and 

 more olivaceous tint than the rest of the shell. 



The H. Webbiana has a greater affinity with the H. 

 cuticula, Shut tl., of the Canarian Group, than with anything 

 else with which I am acquainted ; and, although abundantly 

 distinct, there can be little doubt that the two species have 

 something in common. The H. cuticula, however, is a great 

 deal smaller, being in fact comparatively diminutive ; and, 

 although perhaps not quite so shining, it is very much thinner, 

 paler, greener, more pellucid, and more Vitrina-like ; its keel 

 too is not only more compressed, but also not completely merged 

 into the suture at the penultimate volution, it being traceable 

 up the spire (which is relatively a trifle more elevated) ; and its 

 peristome is not reflexed. 



( Leptaxis, Lowe.) 



Helix chrysomela. 



Helix osnostoma, Lowe (olim), in litt. 



chrysomela, Pfeiff., Mon HeL i. 281 [sedvid. p. 447] 



(1848) 



Lowe, Proc. ZooL Soc. Loud. 167 (1854) 



fluctuosa, Alb., Mai. Mad. 82, t. 17. f. 13-14 (1854) 

 var. a. chrysomela, Paiva, Mon. Moll. 



Mad. 19 (1867) 

 var. (3. fluctuosa. 



Helix fluctuosa, Lowe, Ann. Nat. Hist. ix. (1852) 

 Id., Proc. Zool. Soc. Lond. 167 (1854) 



Paiva, Mon Moll. Mad. 19 (1867) 



Habitat Portum Sanctum, hodie recens non inventa ; in solo 

 calcareo semi-fossilis copiose reperitur. 



The H. chrysomela has been found hitherto only in a subfossil 

 state, and only in Porto Santo, where it is extremely common, 

 both in its smaller and its larger phasis. It is to the former of 

 these that the name chrysomela was applied (in 1848) by 

 Pfeiffer (who, however, by mistake cited the species as Brazi- 

 lian), the larger one having been subsequently enunciated by 

 Mr. Lowe, in 1852, under that of fluctuosa, as specifically dis- 

 tinct. And thus, on the principle of priority, Pfeiffer's title 

 takes the precedence, and the race which he described must be 

 treated as the type. And this being the case, it is perhaps 

 somewhat fortunate that they are both about equally abundant, 

 and that it matters but little, therefore, which of them be 

 looked upon as normal. 



Owing to the necessarily bleached condition of semifossilized 

 specimens, it is well-nigh impossible to detect the law of colo- 



