OP THE GALAPAGOS ARCHIPELAGO. 509 



generally smaller size, as well as in the colour of the chin, already mentioned. On the 

 west coast of South America another species is found, S. Jmmboldti, which differs both 

 from S. magellanicus and S. mendiculus in having only one white band crossing the 

 throat instead of two. In this respect the Chilian bird agrees closely with the true 

 S. demersus of the Cape of Good Hope, from which it only differs in having the super- 

 ciliary white line narrower. 



Dr. Elliott Cones, in his monograph of the Spheniscidae, published in the ' Proceedings 

 of the Academy of Natural Sciences of Philadelphia ' (1872, p. 211), unites the Chilian 

 bird with the true S. demersus of the Cape of Good Hope, and treats S. magellanicus as a 

 variety of the same species. This view does not, in my opinion, give the real relationship 

 these birds bear to one another. aS'. magellanicus in its adult dress can at once be 

 distinguished from either S. demersus or S. Jmmboldti by the additional black band 

 which crosses the throat ; and this also forms a distinctive character in S. mendiculus. 

 Dr. Coues likewise says that S. magellanicus is found in the same localities as S. de- 

 mersus (in which he includes S. Jmmboldti). My experience, however, shows that 

 S. megallanicus is entirely replaced on the west coast of America by S. Jmmboldti, and 

 is restricted in its range to the Falklands and the extreme south of South America. 



As regards the retention of the name Jmmboldti (given by Meyen to the Chilian 

 Penguin), I may say that I do so in preference to adopting the name cJiilensis, supposed 

 to have been bestowed by Molina on the same species. Molina's species are too inade- 

 quately described to warrant his names being substituted for others about which no 

 doubts hang. Moreover I question the propriety of any deduction which might be made 

 from the signification of the name cJiilensis standing in the place of a good description. 



The figure is taken from a typical specimen brought to Europe by the Swedish frigate 

 ' Eugenie,' and now in our collection. 



VII. Concluding Remarks. 



Before concluding this paper a few conjectural remarks on the process by which these 

 islands have become tenanted with bird-life may not be out of place. 



Considering their purely volcanic nature, it cannot reasonably be doubted that these 

 islands have always been islands since they emerged from the sea. Such is Mr. Darwin's 

 view ; and it is fully indorsed by Dr. Hooker and others. The birds that are now found, 

 being related to American birds, must have emigrated thence and become modified by 

 the different circumstances with which they became surrounded. The oldest immigr^ints 

 seem to be indicated by their generic difference from their continental allies, the more 

 modem comers by their merely specific distinctness, and the most recent by their identity 

 with birds now found on the adjoining continent. On this view the islands were first 

 taken possession of by individuals of the parent stock of CertJiidea and Conirostrum, 

 Geospiza and Guiraca, CamarJiyncJius and NeorJiyncJius. Then came perhaps the 

 ancestors of Buteo ; after these followed those of Mimus, PyrocepJialus, and Myiarclius. 



