MADEIRAN GROUP. 119 



Deserta, the 6 s . saxipotens ' of this list. The present variety 

 (or ' S. pulchra,' Paiva) is smaller than any of the foregoing ones, 

 but not so small as the subfossil form from the Southern Deserta ; 

 and it is generally highly decorated, the ground-colour being 

 often of a comparatively clear yellowish tinge, with the two 

 darker bands broadly and abruptly defined. But, owing to the 

 incrustation of dirt with which it is the habit of the species, 

 more or less, to encase itself (and which perhaps is more appa- 

 rent in this particular variety than in the others), the brightness 

 of its ornamentation is not usually very apparent until the 

 shells have been well cleaned. 



Lastly, in the muddy deposits on the top of the Southern 

 Deserta there is a very dwarfed subfossil form of the H. vulgata, 

 smaller than even the ' 8. pulchraj which I would cite as the 

 ' var. s. saxipotens.' In addition to its comparatively diminu- 

 tive bulk (adult examples measuring from about 4 to 5 lines 

 across the broadest part), its umbilicus is relatively much more 

 reduced than in the other phases of the shell ; and, so far as I 

 can judge from white and practically colourless specimens, its 

 two bands are (or, rather, were) narrowed and line-like. Whe- 

 ther this still exists in a living condition I am unable to say ; 

 but as the Baron Paiva alludes to a small state of the H. vul- 

 gata as recent on the Bugio (though treating it as identical 

 with the 4 S. pulchra ' from the north of Madeira), it is not 

 unlikely that it may yet linger on. 



Helix nitidiuscula. 



Helix nitidiuscula, Sow., Zool. Journ. i. 57. t. 3. f. 4 



(1824) 

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



f. 5 (1831) 



Pfei/., Mon. Hel. i. 197 (1848) 

 Lowe, Proc. Zool. Soc. Lond. 174 (1854) 



nitidiuscula, var. 7., Alb., Mai. Mad. 52. 1. 14. f. 4-6 



(1854) 



? Hartungi, Alb., I.e. 42. t. 10. f. 26-28 (1854) 

 lurida, Paiva, Mon. Moll. Mad. 75 (1867) 



Habitat Portum Sanctum ; in calcareis et graminosis sub 

 lapidibus degens. In statu semifossili copiose reperitur. 



This has generally been regarded as the Porto-Santan repre- 

 sentative of the common H. vulgata of Madeira proper and the 

 Desertas, and perhaps in reality it may be; nevertheless its 

 characters (not only of size and contour, but also of colour 

 and sculpture) are so unmistakeable and well-marked, that 

 I scarcely see how a mere supposition can be made use of 



