138 



CHIM^ROID FISHES AND THEIR DEVELOPMENT. 



evolved a long way in the direction of the Chimseroid. On the other hand, we 

 must leave entirely doubtful whether Janassa was still retaining the features of an 

 ancestor which gave rise to the Chimseroid, or whether it was a form which was 

 becoming still more Chimaera-like than its ancestor just as Lepidosiren has 

 become more like the amphibian than has the more primitive Ceratodus. 



123 I2 4 



125 



Figs. 121-125. Association of dental plates of late mesozoic Chimaeroids. Tritots represented by shaded areas. 



After specimens in British Museum. Partly after Smith Woodward. 

 121, Ganodui rugulosus ; 122. Elasmodus hunleri ; 123, Edaphodon buclclandi; 124, Ischyodus egertom ; 125, Elasmodectes willetti. 



The Permian fossil Menaspis should also be mentioned in this connection. 

 Whether, however, it can be regarded as Chima^roid has already been considered 

 by the present writer in a recent number of the American Geologist (vol. xxxiv, 

 pp. 49-53). It was there shown that the size of the dental plates of Menaspis 

 (fig. 1 1 5) indicates that the entire region of the fossil inclosed with spines is to be 



