394 TEST ACE A ATLANTIC A. 



section (measuring about 7 lines across its broadest part), 

 and one which was found abundantly by Mr. Lowe and myself 

 in Gromera, namely 'on the dry rocky slopes immediately 

 above, and around, San Sebastian, particularly on the northern 

 side of the ravine ; and it appears to have been met with in the 

 same island by Fritsch. 



The //. discobolus is very closely related to the H. afficla 

 of Palma ; but apart from its larger size, it may be recognized 

 from that species by its umbilicus being wider and more 

 spirally visible, and by its volutions being seven in number 

 instead of only six. 1 



( Caracollina, Beck.) 



Helix lenticula, 



Helix lenticula, Per., Tabl. Syst. Prodr. 37. 154 (1821) 

 subtilis, Lowe, Cambr. Phil. S. Trans, iv. 45. t. 5. f. 



13 (1831) 

 lenticula, d'Orb., in W. el B. Hist. 66. t. 2. f. 10-12 



(1839) 



Pfeiff., Mon. Hel. i. 211 (1848) 



Lowe, Proc. Zool. Soc. Loud. 196 (1854) 



Alb., Mai. Mad. 43. t. 11. f. 9-12 (1854) 



1 I may just notice, in this particular place, the H. marcida of Shuttle- 

 worth, {Bern. Mitth. 291 ; 1852), a single imperfect example of which, in the 

 Museum at Marseilles, is supposed to have come, in all probability, from the 

 Canaries. Species thus miserably represented (the H. marcida being both 

 immature and unique), and resting upon evidence so completely untrust- 

 worthy, ought never to be admitted at all into the fauna of any country in 

 which accuracy of habitat is absolutely essential ; and I at least will not con- 

 sent to have anything whatever to do with it. Mousson, after including it 

 in his Canarian monograph, adds : 'La description de cette espece, qui n'est 

 guere connue des malacologues, repose sur un seul individu incomplet, et dont 

 1'origine precise est inconnue. Le test strio-granuleux, garni de petits poils 

 velus, et la forme generale multispire, perforee, mais non carenee, la range 

 suivant 1'auteur dans le voisinage de YH. hispidula, Lam. ; mais elle en 

 differe par ses dimensions toutes different es, par la tenuite^de son test, et son 

 duvet plus court et dense.' It is of course by no means impossible that 

 future observations may prove the H. marcida to be Canarian ; but, mean- 

 while, the evidence for its haUtat is altogether so loose and insufficient that 

 no truthful monographer could well do otherwise than decline to receive it 

 into his topographical catalogue. 



And I may also include, along with the H. marcida, a second Helix, which 

 comes under precisely the same category, the H. Melolontha of Shuttle 

 worth. Like the other it is unique, and exists only in the Marseilles museum, 

 both of them being manifestly from the collection of M. Terver, whose 

 orchil-infesting species, the habitats of which were so incautiously assumed, 

 have added a terrible amount of confusion, not only to the Canarian but also 

 to the Madeiran fauna. Considering how utterly mistaken he was in the 

 case of the H. tiarella and tceniata, pronouncing them to be Canarian while 

 they are simply confined to Madeira proper, I must be excused if the evidence 

 for the H. Melolontha should appear to me to be quite as unsatisfactory as 

 that for those two species and for the //. marcida. 



