RECENT LITERATURE 
191 
have ever occurred in the Old World. In each of them the tooth structure rep- 
resents a peculiar and specialized type, while in the true Hystricidce the teeth 
are more primitive than in any other known hystricoids. Derivation of the 
Old World porcupines from these American rodents cannot therefore be re- 
garded as even a remote possibility. Hence it is scarcely necessary to give 
special consideration to the curious idea that the arboreal South American an- 
cestors of Hystrix may have become terrestrial and fossorial while traversing 
trans-Atlantic steppes. Among the few described fossil American squirrels there 
is none whose characters furnish any proof that it was ancestral to the African 
genus Xerus. Finally the assumption that the Hystricidce originated in the 
American Miocene is rendered unnecessary by the fact that two hystricoid 
genera, 1 Phiomys and Metaphiomys, are known from the Egyptian Oligocene. 
While these Egyptian animals cannot now be definitely referred to any family, 
and the teeth are too specialized to have given rise to the type of dental structure 
found in Hystrix and its allies, the presence of such fossils at this horizon shows 
that the hystricoid group is so ancient in the Old World that the supposed Ter- 
tiary migrations from South America are not required to explain its history. 
Analysis of the evidence advanced in demonstration of the other migrations 
appears to reveal an equal degree of inconclusiveness. The history and distribu- 
tion of the zalambdodont insectivores, for instance, which leads Professor 
Joleaud to map a route from central North America through the West Indies to 
West Africa, convinces Doctor Winge^ that the group originated in the Old World 
and crossed to America by way of northern Asia. Another example : Kalobatip- 
pus prcestans has been found in Oregon; K. agatensis, a “more advanced” form, 
has been found in Nebraska; therefore the animals migrated from the Pacific to 
the Mississippi. By a continuation of this reasoning the group is carried east- 
ward to Europe and thence to China.® Similar evidence is supposed to show that 
early mastodons moved from Egypt westward to Florida and Nebraska. 
Surmises and inaccuracies^ such as those which form the substance of this 
paper will not deceive persons who have some knowledge of mammals living and 
extinct. Supported as they are, however, by the reputation of the Revue generate 
des Sciences and by the clearness and apparent authoritativeness of both the maps 
and the text, they are capable of spreading a wholly wrong impression among less 
informed readers. Mammals have not been shown to furnish the evidence needed 
to prove that trans- Atlantic land masses occurred in Tertiary times; neither is it 
clear that an explanation of their distribution is made more simple by the as- 
sumption that such land existed. The enormous blank spaces in the geological 
record allow, it is true, ample room for conjecture, but this is no justification 
^ See Miller and Gidley, Journ. Washington Acad. Sci., vol. S, p. 445. July 
19, 1918. 
^ Vidensk. Medd. fra Dansk naturh. Foren., vol. 68, p. 163, 1917. 
® “Ainsi Kalobatippus-Anchitherium aurait immigre de la c6te pacifique au 
Mississippi .... puis en Europe par FAtlantique central .... 
enfin en Chine . . . . ” (p. 707). 
^ In summarizing the character of the Antillean fauna (pp. 712-713) the author 
omits all allusion to nine genera of extinct mammals described by Allen, Anthony 
and Miller during the years 1916 and 1917. 
