394 TESTACEA 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 H. discobolus is very closely related to the H. afficta 

 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.^ 



(§ Caracollina, Beck.) 



Helix lenticula. 



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

 „ subtilis, Loiue, Cambr. Phil. 8. Trans, iv. 45. t. 5. f. 



13(1831) 

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



(1839) 

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



„ „ Loive, Proc. Zool. Soc. Lond. 196 (1854) 



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



' 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 siij?jjosc'd to have come, in all jnvhaliUtj/, from the 

 Canaries. Species thus miserably reiaresented (the H. mareida being both 

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

 worthj, 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 monograjDh, adds : ' La description de cette esp^ce, qui n'est 

 gu^re connue des malacologues, repose sur un seul individu incomplet, et dont 

 Torigine precise est inconnue. Le test strio-granuleux, garni de petits jjoils 

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

 suivant lauteur dans le voisinage de VH. hisjndnJa, Lam. ; mais elle en 

 diff^re parses dimensions toutes differente-^, 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 II. marcida to be Canarian ; biit, mean- 

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

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

 into his topograijhical catalogue. 



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

 comes imder 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 tcrniata, — pronouncing them to be Canarian while 

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

 for the //. Melolontha should appear to me to be quite as imsatisfactory as 

 that for those two sj^ecies and for the II. marcida. 



