4 TEST ACE A ATLANTIC A. 



exceptionally developed in the Madeiran group and which is 

 present also, though more sparingly, at the Canaries, is a tact 

 which Bhould particularly he noticed ; as well as the occurrence 

 at the Azores and Canaries of the Bidimus variatus, W. et B., 

 and of that singular little species the Hydroccena gutta, — 

 which, of all the members of the Gastropoda, is perhaps the 

 least likely to have been accidentally naturalized. As for the 

 AuriculidcB, which seem to he much the same in the three 

 archipelagos, I lay hut little stress upon them, — for those 

 littoral forms, which in their modus vivendi are practically 

 marine, have almost everywhere a wide geographical range. 



These few instances, however, of course do not embody all 

 that the archipelagos have in common, — for they are principally 

 ' Atlantic ' forms, from which the strictly European element has 

 been eliminated. If we take the actual species into account 

 which the Azores (even as hitherto imperfectly known) would 

 appear to possess conjointly with the more southern groups, we 

 shall find that there are about 26 which occur equally in the 

 Azores and Madeiras, and about 19 in the Azores and Canaries; 

 which (taking the European element for what it is worth) 

 undoubtedly shows an amount of affinity between the three 

 archipelagos which cannot well be ignored. The Eev. H. B. 

 Tristram, in his account of the Pulmoniferous Gastropods of the 

 Azores, published in Mr. Grodman's volume, can scarcely have 

 had very reliable data to draw upon in instituting his compari- 

 son between the Azorean fauna and those of the two archipelagos 

 the next in succession to the south of it, — for he asserts that it 

 has only 7 species in common with the Madeiras, and 4 with 

 the Canaries ; whereas, according to my computation, it pos- 

 sesses (as just stated) at least 26 in common with the Madeiras, 

 and 19 with the Canaries M Or, if we regard the Madeiras and 

 Canaries as integral portions of a single ' Atlantic province,' no 

 less than 31 species out of the 71 of which the Azorean fauna is 

 made up permeate more or less of the latter, — 5 of them ranging 

 even to the Cape Verdes, and 5 to St. Helena. 2 



1 The 26 species which are found equally in the Azores and Madeiras are 

 these: — Arion ater, TA/max gagates, maximus, flavits, and agrestis, Testacella 

 Maugei, Hyalina cellaria and crystallina, Patula rot un data and pusilla, Helix 

 pulchella, eruhescens, aspersa, pisana, armillata, pampercula and lentieula, 

 Bulimus ventricosus, Stenogyra decollate/,, Achatina lubrica, Balsa perversa, 

 Pupa microspora and anconostoma, AuricuM eequalis and vesperfnna, and 

 Pedipes afra : whilst the following 19 are those which are common to the 

 Azores and Canaries: — Testacella Maugei, Biyalina cellaria and crystallina, 

 Patula pusilla, Helix pulchella, aspersa, lactea, pisana, apicina, paupercula, 

 and lentieula, Bulimus ventricosus and variatus, Stenogyra decollata, Pupa 

 microspora and anconostoma, auricula squalls and hi, -alar, and Hydroccena 

 gutta. 



- Mr. Tristram says, likewise, that -It should be observed that, of all the 

 Pulmonifera of the Azores, Pedipes afer is the only one common to the 



