OF 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. humboldti, 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 Coues, in his monograph of the Spheniscidee, 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. S. magellanicus in its adult dress can at once be 
distinguished from either S. demersus or S. humboldti 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. humboldti). My experience, however, shows that 
S. megallanicus is entirely replaced on the west coast of America by S. humboldti, and 
is restricted in its range to the Falklands and the extreme south of South America. 
As regards the retention of the name humboldti (given by Meyen to the Chilian 
Penguin), I may say that I do so in preference to adopting the name chilensis, 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 chilensis 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. Conciupine 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 immigrants 
seem to be indicated by their generic difference from their continental allies, the more 
modern 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 Certhidea and Conirostrum., 
Geospiza and Guiraca, Camarhynchus and Neorhyachus. Then came perhaps the 
ancestors of Buteo; after these foliowed those of Mimus, Pyrocephalus, and Myiarchus. 
