xni PHYLUM CHORDATA 609 



numerous intermediate forms connect together the Dogs, Civets, 

 Cats, Bears, and Weasels, which, in the existing fauna, appear 

 separated from one another by differences of the most strongly 

 marked character. Several extinct families are recognised, and 

 one extinct order the Creodonta. The latter present resemblances 

 to the Insectivora on the one hand, and to the Polyprotodont 

 Marsupials on the other, such as would appear to indicate a 

 relationship with both of those groups. 



A group of Eocene Mammals of uncertain affinities are the 

 Tillodontia (Fig. 1236), which by some have been elevated to the 



FIG. 123r>. TillOtherium fodiens. Left lateral view of skull. (From Flower, after Marsh.) 



rank of a distinct order. The Tillodontia appear to unite in a 

 remarkable degree, in skull and dentition, ungulate, rodent, and 

 carnivorous characteristics. 



The Rodents were represented in the Tertiary period by all, or 

 nearly all, the principal groups existing at the present day, together 

 with several extinct families. Some of the Tertiary Eodents 

 attained a much larger size than any living members of the order. 



Among the Tertiary Insectivora, in addition to representatives 

 of existing families, are a number of extinct forms. Through these 

 it is possible to connect the living Insectivora with the Creodont 

 Carnivora on the one hand, and with the Prosimii on the other. 



Chiroptera, not differing widely from existing forms, occurred 

 as early as the Eocene. 



Of the Primates, Prosimii occur from the Eocene onwards. 

 A single extinct family is known, comprising Lemuroids which 

 bear a closer resemblance to Insectivora than do the living 

 members of the order. Of the Anthropoidea,, the Hapalidae and 



