72 BIOLOGICAL LECTURES. 



James, Jervis, Barrington, Charles, Hood, Gardner, Chatham, 

 Bindloe, Abingdon, and Tower. This genus, formerly common 

 on Charles, is now extinct; it has never been seen on Duncan. 

 Mr. Ridgway has studied this genus and found the following : 

 Nearly each island has its peculiar race or species ; and there 

 is never more than one race or species found on a single island. 

 On Jervis and James we find the same species, and this can 

 also not be separated from the Indefatigable-bird ; on Hood and 

 Gardner we have the same bird ; but each one of the other 

 islands shows its own form. This agrees with Tropidurus ; 

 Jervis and James have the same Tropidurus and closest to that 

 of Indefatigable ; Hood and Gardner have identical forms. 



The genus Certhidea was found on Indefatigable, James, 

 Jervis, Barrington, Chatham, Bindloe, Abingdon, and Tower. 

 The specimens on Jervis and James were the same ; but each 

 other island showed its peculiar species. 



The genus Pyrocephalus was found on Albemarle, Jervis, 

 James, Indefatigable, Charles, Chatham, Bindloe, and Abing- 

 don. On Albermarle (.''), Jervis, and James was one species ; 

 all the other islands, with the possible exception of Bindloe, 

 had peculiar species. 



I could give many more examples, but it will be sufficient 

 to mention only a few. 



Phyllodactylus, a genus of the Geckonidae, has been dis- 

 covered so far on three islands, Chatham, Charles, and Albe- 

 marle ; on each of these islands it is represented by a peculiar 

 species. Amblyrhynchus, the sea-iguana, is not identical on 

 all the islands, but has developed peculiar races on Tower and 

 Duncan. 1 The genus Schistocerca of the Orthoptera (Acridi- 

 dae) is the same on the middle islands, but is represented by a 

 peculiar race on the more isolated islands, Chatham, Hood, and 

 Tower.2 



The following table shows the distribution of these different 

 genera : — 



1 Garman, S.: The Reptiles of the Galapagos Islands. Bull. Essex Inst., vol. 

 XXIV, 1892. 



2 Scudder, Samuel H.: The Orthoptera of the Galapagos Islands. Bull. Mus. 

 Comp. Zodl., Harvard College, vol. XXV, No. i, 1893. 



