REPTILES 47 



nection between South America and Africa, is not to be seri- 

 ously considered. The similarity of the Mascarenes and Gala- 

 pagos Testudo may be largely due to insular isolation, the 

 two groups having sprung from a similar cosmopolitan type 

 derived from the nearest continent, the absence of enemies and 

 abundance of food on the islands being favorable to the devel- 

 opment of gigantic races. These races have developed along 

 nearly the same lines. Western South America at present 

 lacks the genus, and paleontology is as yet silent as to its occur- 

 rence or the time of its disappearance there. Assuming that 

 the Galapagos reptile fauna has been chiefly derived from ma- 

 terial carried by ocean currents, the present direction of these 

 currents would favor its derivation from South America south 

 of the equator. So little of the fauna and flora is allied to West 

 Indian and Central American forms, however, that it is im- 

 probable that during those geological epochs (Tertiary or older) 

 when the Americas were separated by the submergence of part 

 of the connecting isthmus an ocean current from the northeast 

 washed the shores of the archipelago and brought with it such 

 forms. The large Central American element in the Galapagos 

 may be traced to the influence of the seasonal shifting of the 

 present currents about the Panama region which not infrequently 

 bring floating material to the islands from that coast. 



The single peculiar species of Gonatodes is most closely allied 

 to G. ocellatus of the West Indies (Tobago). This genus oc- 

 curs along the coasts of Ecuador and Peru. 



Of the five species of Phyllodactylus, four are peculiar and 

 more or less closely related to P. tuberculosus, the non-peculiar 

 species which is distributed along the west coast of Mexico, and 

 Central and South America southward to Ecuador. 



Tropidurus is distinctly a Neotropical genus with several 

 Peruvian and Ecuadorian species. All the Galapagos species 

 are peculiar and closely related forms, their nearest continental 

 allies being perhaps some of the Peruvian species. 



The genus Conolopkus according to Garman 1 is nearest the 

 Neotropical genus Enyalioides which is a common Ecuadorian 

 inhabitant. This affinity is especially well marked in the young 



1 Garman, Bull. Essex Inst, xxiv, 1892, p. 3. 



