380 THE OSTRACODERMS. 



edly represents the contents of the stomach. A microscopic examination failed 

 to reveal any definite structures in it, such as diatomes or fragments of bones or 

 shells. It has the same appearance as the remnants of plants seen outside the 

 body, and like them readily burns when heated, leaving a whitish ash. We may 

 therefore infer that Bothriolepis fed on the ferns or other water plants that were 

 so abundant in the places where they have been found. Such a diet was appa- 

 rently better suited to the peculiar structure of their jaws than any other. 



We therefore again come to the same conclusion that was reached in another 

 way, namely that there is a close resemblance between the ostracoderms and 

 the amphibia, for Bothriolepis, with its big head and small tail, its vegetable diet, 

 the peculiar action of its lower jaws while feeding, and in its general mode of life, 

 greatly resembles the tadpole larva of the common frog. The most striking 

 difference between them is the apparent absence in the tadpole of the large 

 cephalic appendages, but these organs are probably represented by the sucking 

 discs, which in turn are comparable with the "balancers" of Amblystoma and 

 other urodeles (Fig. 169), and with the long filamentous cephalic appendages 

 of Dactylethra or Zenopus. (Fig. 170.) 



