2 34 THE HISTORY OF CREATION, 



many (at Degerloeh, near Stuttgart, in 1847), later also in 

 England (at Frome), in 1858. Similar teeth have lately 

 been found also in the North American Trias, and have been 

 described as Dromatherium sylvestre. These remarkable 

 teeth, from the characteristic form of which we can 

 conclude that they belonged to an insectivorous mammal, 

 are the only remains of mammals as yet found in the older 

 secondary strata, namely, in the Trias. It is possible, 

 however, that besides these many of the other mammalian 

 teeth found in the Jura and Chalk systems, which are stiU 

 generally ascribed to Marsupials, in reahty belong to Cloacal 

 Animals. This cannot be decided with certainty owing to 

 the absence of the characteristic soft parts. In any ease, 

 numerous Monotrema, with well-developed teeth and cloaca, 

 must have preceded the advent of Marsupial animals. 



The desig-nation, " Cloacal animals " (Monotrema), has 

 been given to the Ornithodelphia on account of the cloaca 

 which distinguishes them from all other Mammals ; but 

 which on the other hand makes them agTee with Birds, 

 Eeptiles, and Amphibia, in fact, with the lower Vertebrata. 

 The formation of the cloaca consists in the last portion of 

 the intestinal canal receiving the mouth of the urogenital 

 apparatus, that is, the united luinary and genital organs, 

 whereas in all other Mammals (Didelphia as well Mono- 

 delphia) these organs have an opening distinct from that 

 of the rectum. However, in these latter also the cloaca 

 formation exists during the first period of their embryonal 

 Hfe, and the separation of the two openings takes place only 

 at a later date (in man about the twelfth week of develop- 

 ment). The Cloacal animals have also been called " Forked 

 animals" because the collar-bones, by means of the breast 



