334 TEST ACE A ATLANTIC A. 



(§ Iberus, Monf.) 



Helix digna. 



Helix digna, Mouss., Faun. Mai. des Can. 68. pi. 4. f. 3 

 (1872) 

 „ Pfeiff., Mon. Hel. vii. 304 (1876) 



Habitat Gromeram; in statu semifossill a cl. Fritsch re- 

 perta. 



Detected by Fritsch, in a subfossil state, in Gomera, and a 

 species of peculiar interest geographically as belonging to much 

 the same type as the Porto-Santan H. Wollastoni, Lowe, and 

 forensis, Woll., from the Madeiran Group, and the Mediterra- 

 nean H. scabriuscula, Desh. It appears however to be con- 

 siderably larger than the H. Wollastoni ; ' le sommet,' says 

 Mousson, ' est plus obtus, forme par un nucleolus relativement 

 bien plus gros, le nombre des tours n'est que de 4 au lieu de 5 

 et ils grandissent plus promptement, la sculpture est moins 

 reguliere et plico-costulee, au lieu d'etre simplement costulee, 

 la surface intercostale n'est pas finement granulee, mais inegale- 

 ment rude, la base, quoique de forme tres semblable, est plus 

 renflee autour de l'espace central, le bord basal de l'ouverture se 

 courbe plus fortement vers l'insertion columellaire et se reflechit 

 plus largement et plus subitement pour cacher la perforation. 

 Malgre ces differences, YH. digna constitue une des analogies 

 les plus intimes entre les deux groupes d'iles.' (I. c. 69) 



Helix Berkeleyi. 



Helix Berkeleii, Lowe, Ann. IS at. Hist. vii. 108 (1861) 

 Pfeiff., Mon. Hel. v. 265 (1868) 

 „ Berkelei, Mouss., Faun. Mai. des Can. 80. pi. 4. f. 7, 



8(1872) 

 „ Berkeleii, Pfeiff., Mon. Hel. vii. 305 (1876) 



Habitat Canariam Grandem ; a Eevdo. E. T. Lowe et meipso, 

 Aprili 1858, inter Maspalomas et Juan Grande, et recens et 

 semifossilis, reperta. 



This curious Helix approaches nothing which has hitherto 

 been detected in these various Atlantic archipelagos; though 

 perhaps it is more nearly related to the H. Wollastoni of the 

 Madeiran Group than to anything else, or possibly to the com- 

 paratively gigantic subfossil H. digna, Mouss. (which however 

 I have had no opportunity of inspecting), from Gomera. Never- 

 theless with even the H. Wollastoni it has very little really in 

 common, — though its discoidal contour, strongly developed 

 keel, and completely closed umbilicus would tend perhaps to 

 affiliate it a little with that species ; whilst in its granulated 



