THE DEVONIAN PERIOD. 



485 



referred to this family, seems to throw much light on its relations in 

 that it possessed oar-like appendages, median eye-pits, and muscu- 

 lar markings that assist in interpreting doubtful features in the Pteraspis. 



The Tremataspis , as interpreted by Patten, had a broad oval shield, 

 with a pair of oar-like swimming appendages, and a relatively small, 

 rather slender trunk, as illustrated in Fig. 216. As in theCephalaspis, 

 the lateral and median eyes and the olfactory pit were close together 

 on the median line, well back from the front margin. 



Perhaps the most curious of all these strange creatures were the 

 pterichthyds (winged fish), of one of which, Bothriolepis, an elegant 

 restoration by Patten is shown in Fig. 217. In this the structure 



Fig. 217. — Reconstruction of Bothriolepis, side view. (After Patten.) 



has been worked out in great detail from a large collection made in 

 New Brunswick. The Bothriolepis had a short head with close-set 

 lateral eyes on movable stalks, an angulated buckler, and a very slender 

 naked trunk bearing two dorsal fins, and a tail of peculiar form. Three 

 pits on the inner surface of the head, between the lateral eyes, indi- 

 cate the presence of a trioculate median eye. There is no sign of 

 vertebrae or of notochord, though the latter may have been present. 

 Many anatomical features suggest relations to the arthropods on 

 the one side, and to vertebrates on the other. 



It is obvious from even the few features here noted that the ostra- 

 coderms differed greatly among themselves, and were probably already 

 an ancient widely divergent line. Their distinct separation from 

 the fishes puts a new phase on their place in the life series. Instead 



