28 TEST ACE A ATLANTICA. 



fragile, than those from S. Miguel) are opake, except the nucleus 

 and the base (which are translucid), and of a uniform pallid or 

 nearly straw-coloured hue, constituting a well-marked variety, 

 the ' 7. minor ' of Morelet. The aperture is a little more 

 rounded in the H. azorica than it is in the cognate forms, and 

 has its columellary margin but very slightly thickened or 

 expanded; and the ultimate volution is rather broader or more 

 developed. 



Helix caldeirarum. 

 Helix caldeirarum, Morel, et Dr., Journ. de Conch, vi. 150 



(1857) 

 azorica (pars), Mouss., Viert. der Nat. Zurich, 165 



(1858) 



Pfeiff., Mai. Bldtt. 81 (1858) 

 caldeirarum, Id., Mon. Hel. iv. 347 (1859) 

 Morel., Hist. Nat. des Acor. 156. t. 2. 



f. 3 (1860) 

 Drouet, Faun. Acor. 152 (1861) 



Habitat S. Miguel ; sub lapidibus in Caldeira de Sete-Ci- 

 dades, rarissima. 



The H. caldeirarum (which measures about 12 millimetres 

 ^across its widest part), although thin and subdiaphanous, is 

 apparently not quite so fragile and pellucid as the azorica, and 

 it is also more appreciably striate ; its surface is of a light 

 uniform corneous-brown, free from paler blotches or irregular 

 markings, but ornamented with a well-defined darker band--- 

 which occupies the dorsal region, or circumference, of the ulti- 

 mate whorl, and runs up alongside the suture of the pen- 

 ultimate one ; its aperture is not quite so rounded ; the 

 columellary margin of its peristome is a trifle thicker or more 

 dilated,^and its last volution is rather less broadly developed. 



It seems to have been only in S. Miguel that the present 

 Helix has hitherto been observed, where it was met with 

 (though sparingly) by Morelet and Drouet, beneath stones, in 

 the Caldeira of the Sete-Cidades. 



Helix niphas. 



Helix niphas, Pfeiff., Proc. Zool. Soc. Lond. 108 (1857) 

 Mouss., Viert. der Nat. Zurich, 166 (1858) 

 Pfeiff., Mon. Hel. iv. 159 (1859) 

 Morel., Hist. Nat. des Acor. 162 (1860) 

 Drouet, Faun. Acor. 153 (1861) 



Habitat S. Miguel (teste PfeifTer) ; ex speciminibus a Dom. 

 Cuming missis descripta. 



