502 TEST ACE A ATLANTIC A. 



whatever to Beparate them from others which had previously 

 been defined and published. 



Tlie additions to the Land Mollusca of St. Helena which 

 were made by myself and Mrs. Wollaston, during our late sojourn 

 in the island, are only three in number, — namely the Hyalina 

 Mellissii, n.s., the Patula pus ilia, Lowe, and the Subulina 

 melaaiuides, n.s. ; for although it is true that the European 

 Helix pidchdla, Mull., which we found abundantly, was not 

 included in Mr. Melliss's enumeration, a single example of it had 

 nevertheless been met with many years ago, by Mr. E. L. Layard 

 (teste Benson, Ann. Nat. Hist, xviii. 1 856), while touching at the 

 island, on his passage to the Cape of Good Hope. It will, how- 

 ever, perhaps, be a matter of some surprise that, in spite of these 

 three genuine accessions, and in spite of three others (the Helix 

 pulcheUa, Mull,, the Stenogyra compressilabris, Bens., and the 

 Achatina Veru, Bens.) which we owe to the researches of Mr. Lay- 

 ard, and of the Helix diance of Pfeiffer's Monograph, my present 

 catalogue numbers absolutely less than Mr. Melliss's did, — con- 

 taining, as it does, only twenty-nine species, as contrasted with 

 his thirty-one. But the explanation of this is to be found in 

 the fact that, according to my estimate of the fauna as placed 

 hitherto upon record, a large proportion of the names which 

 have been assumed (because published) to represent distinct 

 species, are in reality mere synonyms of each other, — some of 

 them not indicating even separate varieties. And if this is truly 

 the case, as I believe it to be, Mr. Melliss's list should have been 

 quoted at twenty-two instead of thirty-one. Two members, 

 however, have been rejected, simply, because no evidence was 

 supplied which renders it even possible to admit them into an 

 accurate and systematic list. These are two slugs, which (in 

 addition to the Limax g agates, Drap.) are said to occur in the 

 island. Even though unidentified with any known forms, and 

 although unaccompanied by any regular and detailed descrip- 

 tion, I might still have entered them as members of the fauna 

 had a single character been given, or so much as an isolated 

 remark, which might have taken the place of a partial diag- 

 nosis ; but without anything at all by which they could by any 

 possibility be recognized, and knowing as I do how the same 

 slug may put on different prima facie aspects according to its 

 exact age and degree of development, I scarcely see that I should 

 have been justified in treating them as properly ascertained ex- 

 ponents of the Pidmonobranchiata of St. Helena; and I have, 

 therefore, preferred to leave them unnoticed. 



In the list which is given at the close of this Section, I 

 have, as in the preceding catalogues, appended an asterisk 

 (*) to the species which have been met with also in a subfossil 



