MADEIRAN GROUP. Ill 



surface (both of which may be chiefly due to the long process of 

 semifossilization to which it has been exposed), and apart also 

 from its comparatively gigantic stature, the H. Boivdichiana is 

 a trifle more inflated and globose than the punctulata, as well 

 as more coarsely sculptured ; its basal volution descends some- 

 what more abruptly in front, causing the aperture to be less 

 regularly and uniformly rounded (or more subsinuate) below 

 the insertion of the right margin ; and the peristome is more 

 incrassated, — especially the lower, or columellary, portion of it, 

 which is conspicuously broader than in the H. punctulata. 



Helix punctulata. 



Helix punctulata, Sow., Zool. Journ. i. 56. t. 3. f. 2 (1824) 

 „ „ Lowe, Cambr. Phil. S. Trans, iv. 52. t. 6. 



f. 6 (1831) 

 Pfeiff., Mon. Eel. i. 194 (1848) 

 „ „ Lowe, Proc. Zool. Soc. Lond. 172 (1854) 



„ „ Alb., Mai. Mad. 50. t. 13. f. 17-19 



(1854) 

 „ „ Paiva, Mon. Holl. Mad. 73 (1867) 



var. avellana, Lowe. 



Helix punctulata, var. /3., avellana, Loive, Proc. Zool. Soc. 



Lond. 172 (1854) 

 „ „ var. a. avellana, Paiva, 1. c. 74 (1867) 



Habitat Portum Sanctum (insulasque parvas adjacentes), et 

 Desertam Australem ; in illis vulgatissima. Semifossilis, et in 

 Portii Sancto et in Deserta Australi, parce reperitur. 



I have already pointed out in what the H. punctulata, 

 Sow., differs from its nearly-allied but comparatively gigantic 

 analogue, — the (extinct) H. Boivdichiana, Fer. In point of 

 mere colour the two forms, as we now view them, are of course 

 totally unlike ; but that is simply without significance (as 

 regards the qucestio vexata of their specific identity, or other- 

 wise), the process of subfossilization to which the Bowdichiana 

 has been so long exposed having bleached it into a more or less 

 chalky or calcareous white. 



The H. punctulata varies a good deal in its markings, and 

 (like so many of the Helices) it has now and then a pure, 

 whitish-yellow, unmaculated, albino state ; but, in a general 

 sense, it may be said to be of a deep, warm, reddish-brown hue, 

 with the central portion beneath more or less pale, and with a 

 narrow (often indistinct) medial band, which is lost sight of in 

 the suture of the penultimate volution (just above the aperture), 

 of the same paler tint ; — under which circumstances the shell 

 may be described as unifasciate. Occasionally however the 



