90 Prof. A. Mousson on the Molluscan Fauna of the Canaries, 



(4.) The species cyclodon, Webb^ Despreauxii, D'Orb., mode- 

 ratdy MSS., argonautula, Webb, granostriata, MSS., have no 

 kindred forms in the Madeiras*. On the other hand, they unite 

 — as, however, well-distinguished forms — with certain S. Euro- 

 pean types. 



(5.) The same may be said of the horny-shelled H. diaphana. 

 Lam., afficta, Fer., fortunata and discobolus^ Shutt., hispidula, 

 Lam. With the exception of the universally diffused H. lenticula, 

 Fer., nothing similar occurs in Madeiraf. On the other hand, 

 the S. European H. lens and ciliata are more nearly related. 



(6.) In Bulimus, the extensive groups of obesatus and variatus, 

 Webb, uniting with the European B. montanus and obscurus, 

 are quite wanting in Madeira and Porto Santo. Strange to say, 

 however, they again find, though indeed in a remarkably aber- 

 rant form {B. eganeuSy Alb.), a representative in the Azores. 



(7.) Cyclostoma Icevigatum, Webb, belongs to the type of the 

 European C. elegans, also occurring in the Canaries J, but not 

 mentioned as a Madeiran species. 



These few observations may suffice to indicate the nature of 

 the Canarian fauna in comparison with both the S. European 

 and Madeiran, as also its far greater affinity with the first than 

 with the last. To complete more perfectly its characterization 

 and comparison, additions are still wanting to our information 

 in three directions : 1st, with respect to the species of the less- 

 visited islands ; for, excepting Teneriffe and Palma, not one can 

 really be considered as exhaustively explored ; 2ndly, with refer- 

 ence to the Molluscan fauna of the Cape de Verdes, which, con- 

 sidering their position over against the continent, should have 

 the nearest resemblance to the Canaries, though their more 



Canarian) H. Michaudi, Desh., is a genuine, nay, typical species of the 

 same group, viz. Lemniscia, Lowe. — Tr. 



* H. argonautula, Webb, certainly, and H. granostriata probably, be- 

 long to the peculiarly Madeiran group Discula. H. cyclodon, Webb, is of 

 extremely doubtful origin as to habitat, and it is probably as little entitled 

 to a place in the Canarian as in the Madeiran fauna. The assertion in the 

 text, therefore, relatively to the Madeiras can be fully admitted only in the 

 case of H. Despreauxii, D'Orb., of which moderata is merely a variety, and 

 which, like H. cyclodon, D'Orb., belongs to the restricted group Crenea, 

 Alb., typified by H. elegans, Drap.,— a group of which Madeira certainly 

 possesses no true representative. — Tr. 



t It may be doubted whether all the species above enumerated belong 

 really to the same group; and some will perhaps prove to have their 

 genuine counterparts in Madeira. — Tr. 



X Whether C. Icevigatum, Webb, be really distinct from C. elegans 

 (Miill.), seems very questionable. Certainly one species only of this type 

 has offered itself to the combined researches of myself and Mr. Wollaston 

 in any of the seven Canarian islands. In the Madeiran nothing of the sort 

 occurs. — Tr. 



