ANOMALOUS REPTILES 117 



or knob-like process, instead of by two, as in the Labyrinthodonts 

 and all the amphibia. 



Palaeontologists have concluded that Labyrinthodonts, Anomo- 

 donts, and Monotreme mammals are all descended from some 

 common amphibian stock. If this theory is true, the Anomodonts 

 retained, while they were yet in existence, structures showing a 

 relationship with mammals or a foreshadowing of them, which in 

 all other reptiles have been altogether lost. 



Palaeontologists are often greatly helped in their studies by 

 comparing extinct types of life with some of the living types which 

 are very old-fashioned and, one would think, ought to have become 

 extinct ages ago, but fortunately have not ! We mentioned just 

 now the Tuatara, as a case in point ; another still more important 

 case is that of the Monotreme mammals the curious Duckbill 

 and the Spiny Ant-eater (Echidna) of Australia (which, of course, 

 is not one of the true Ant-eaters). These two remarkable egg- 

 laying mammals show some wonderful points of resemblance to 

 the Anomodonts points which cannot, however, be explained 

 without entering too much into dry details of Anatomy. Indeed, 

 they are a great puzzle to naturalists, and one hardly knows 

 whether we ought to call them reptiles or mammals; but since 

 they do suckle their young ones (after a primitive fashion, though), 

 they have been placed with the latter; still it requires a slight 

 stretch of imagination to look upon an egg-laying creature as a 

 mammal. 



Leaving now the Anomodonts, we pass on to consider another 

 order the Proterosauria. In America and France the subject 

 has been studied by Professors Cope l and Gaudry. The former 

 palaeontologist has described, amongst others, such remarkable 



1 History of the Vertebrata of the Permian Formation of Texas, by Professor 

 E. D. Cope, Pal. Bull, No. 32. 



