CANARIAN GROUP. 349 



Habitat Teneriffam ; a cl. Grasset lecta. 



It seems far from improbable that this Helix, which was 

 taken by M. Grasset in Teneriffe, represents but an accidental 

 state, or variety, of the H. plicaria, in which the umbilicus is 

 unclosed-over by the expanded lamina of the lower lip ; never- 

 theless its exposed or open umbilicus makes it in some degree 

 connective between that species and the H. planorbella ; though 

 its affinities are clearly more with the plicaria than with the 

 latter. 



After his diagnosis of the H. inutilis, Mousson remarks : 

 1 Cette espece se place entre la planorbella et la plicaria, 

 Lam., en se rapprochant toutefois plus de la seconde. Elle se 

 distingue des deux par un enroulement plus lache, et un bord 

 basal entierement detache. En outre elle differe de la planor- 

 bella par une ouverture phis grande et une costulation ruguese 

 et plus grossiere ; de la plicaria par contre, dont elle partage 

 entierement la sculpture, par l'ombilic tres ouvert, malgre la 

 large reflexion du bord, par la forme plus reguliere de l'ouverture 

 et le rapprochement des insertions marginales jusqu'a moins de 

 -^ du pourtour. II me semble peu vraisemblable que ces differ- 

 ences ne soient qu'individuelles, dues a un developpement anor- 

 rnal, bien que je n'aye vu qu'un individu de cette espece, 

 provenant, suivant M. Tarnier, comme la plicaria, de Teneriffe.' 



Helix planorbella. 



Helix planorbella, Lam., Hist. viii. 66 (1822) 

 „ strigata, var. 13, Fer., No. 162. t. 67. f. 8 

 „ planorbella, Mouss., Faun. Mai. des Can. 76. pi. 4. 

 f. 18, 19 (1872) 

 var. (3. incisogranulata, Mousson. 



Helix planorbella, Desk., Fer. Hist. i. 45 (1851) 



>, Pfeiff., M on, Hel, y. 364(1868) 



„ Id., Novit. Conch, ii. 297. t. 72. f. 8-12 



,. var. incisogranulata, Mouss., I. c. 176 



(1872) 



Habitat Teneriffam, et Gomeram ; in ilia var. /3., sed in 

 hac (sec. Mousson) status normalis. 



This is one of the species which were not obtained by either Mr. 

 Lowe or myself, and one which I have been unable to procure 

 for examination ; but according to Mousson it presents two 

 totally distinct forms, — one of them peculiar to Gomera, with 

 the costse simple or ungranulated, which he believes to cor- 

 respond with the Lamarckian type, and the other, which is 

 more depressed and keeled, and has the ridges distinctly 

 sculptured, to Teneriffe. This latter phasis, figured by Pfeiffer 



« 



