172 



ANIMAL LIFE PAST AND PRESENT. 



not improbable that in this group of extinct mam- 

 mals we may really have forms allied to the ancestral 

 Monotremes. Some further evidence in favour of this 

 view has, indeed, been recently published in the 



United States, where cer- 

 tain bones of these mam- 

 mals have been described 

 as the coracoid and inter- 

 clavicle an interpreta- 

 tion which, if correct, will 

 prove their affinity to the 

 Monotremes. For the pre- 

 sent we must, however, 

 wait in the confident ex- 

 pectation that future dis- 

 coveries will some day 

 reveal to us the remains 

 . of extinct animals allied 



51. Palatal view of the imperfect 

 skull of a Secondary Mammal (Trityl- on the Oil 6 hand to the 

 odon). Two-thirds natural size. 



existing Monotremes, and 



on the other so closely connected with the Anomo- 

 dont reptiles and the Labyrinthodont amphibians as 

 to render it very difficult to give a definition of either 

 mammals, reptiles, or amphibians. 



