246 ORIGIN OF LIFE IN AMERICA 



within recent years the remains of a small insectivore have 

 been met with in the early Tertiary Santa Cruz deposits of 

 Patagonia. This mammal, according to Professor Scott,* is 

 genetically related to the African golden moles. The South 

 American Necrolestes, as it has been called, is certainly more 

 primitive in structure than its African relations. Moreover, 

 in .western North America fossil mammals have been dis- 

 covered both in Oligocene and Miocene strata which have been 

 referred to the same family Chrysochloridae. It is true that 

 Dr. Matthew f is now inclined to place the Oligocene Apter- 

 nodus among the nearly related family Centetidae, but the two 

 other genera Xenotherium and Arctoryctes are still looked 

 upon as true chrysochlorids. A possible land connection 

 between Africa and South America will be discussed later on. 

 Whether Patagonia was the original home of the chryso- 

 chlorids or South Africa we cannot tell, but the family may 

 possibly have spread from South America to North America 

 by utilising the hypothetical land bridge that I think lay to 

 the west of the present continent. 



A few words of appreciation of the splendid work that has 

 been done in making us acquainted with the rich fauna and 

 flora of Central America are due to Mr. Godman. For years 

 he and Mr. Salvin laboured with great industry and at con- 

 siderable expense in bringing together an immense collection 

 of vertebrates and invertebrates, subsequently publishing the 

 series of beautifully illustrated volumes of the " Biologia 

 Centrali- Americana " in which the results of their studies were 

 made known to the scientific world. In the volume describing 

 the botany of Mexico and Central America there is an excel- 

 lent summary dealing with the constituents of the flora and 

 their relationships. No such summary has been attempted in 

 the other volumes, so that Mr. Hemsley's account of the plants 

 of Mexico and Central America is of particular value to those 

 who are engaged in a study of the zoogeography of that region. 



The first item of interest is one which we have noticed 

 occasionally among apparently very ancient groups of North 

 American animals. Genera like the amphibians Spelerpes 

 and Amblystoma, which have their headquarters in Mexico, 



* Scott, W. B., "Eeport of Princeton Expedition," Vol. V. 

 t Matthew, W. D., "The Skull of Apternodus," p. 35. 



