482 Proceedings of the Royal Irish Academy. 



Among tlie birds, which have arrived in Ireland with the southern 

 migration, may be mentioned the Dipper ( C«?c?2/s aqimticus). It 

 inhabits the Pyrenees, France, the south-west of England and "Wales, 

 Ireland, Scotland, and the outer Hebrides, and just enters the western 

 parts of Germany, Holland and Belgium. Unlike the animals con- 

 sidered above, it has not, however, originated in South-western Europe. 

 It has only migrated to Ireland from there, though a race known as 

 Cinclus melanogaster may have developed in South-"Wcstern Europe 

 and have spread north more recently, for, according to Dr. Bowdler 

 Sharpe, it is only found in the east of England. Beyond the British 

 Isles it is known from Scandinavia and even Northern Tlussia besides 

 the Spanish Peninsula. A second race ( Cinclus albicollis) inhabits the 

 whole Mediterranean region, spreading north into Switzerland, and it 

 forms the link as it were between the true Dipper and the Asiatic 

 form, Cinclus caslimeriensis. The other species of Cinclus are divided 

 between Asia and America, but the genus is probably of Asiatic origin. 

 The path of migration from Asia into Europe across the Aegean Sea, 

 followed by the Dipper was, as I have mentioned (76 c, p. 458), the 

 regular route at that time. It remained indeed the only means of 

 communication between the tw^o continents for a long while. 



I was under the impression that these same conditions prevailed 

 during the whole Pliocene Epoch and only changed then ; but Prof. 

 Charles Deperet is of opinion that the extensive land-connexion which 

 prevailed in the Mediterranean during the Miocene Epoch ceased to 

 exist in early Pliocene times. I have not ascertained the reasons for 

 his thinking that such had been the case, but I presume that he holds 

 the Sicilian Pliocene deposits to indicate that a submergence must have 

 occurred then, I would fain accept the verdict of such a high authority, 

 but as those deposits contain northern species of mollusca, which must 

 have reached the Mediterranean from the Atlantic, I venture to think 

 that their true age has still to be decided, after it is definitely known 

 when these mollusca entered the Atlantic. 



The bullfinch {Pyrrhida euroimea) has a distribution very similar 

 to that of the Dipper, but whereas the latter only took part in the 

 southern migration, a fonn of the other known as the Russian bullfinch 

 {Pyrrhula major) joined also the Siberian migration. Such cases 

 occur again and again, and are most instructive. The ordinary bull- 

 finch inhabits the Mediterranean region and Western Euroj)e. One 

 other species or race, as some prefer to call it, inhabits the Continent 

 of Europe and one the Azores, but all the other seven species are 

 Asiatic. We have here, therefore, another instance of a bird of 



