FISHES 



Dipterus (Fig. 142), an example of 

 this group, is very like the modern 

 lung fishes, which have dwindled to 

 three genera, one in South America, 

 one in Africa, and one in Australia. 

 A remarkable series of fishes, the 

 Arthrodira, are regarded, though 

 with some doubt, as a division of 

 the lung fishes. One of the best- 

 known members of this group is 

 the European genus Coccosteus 

 (Fig. 143), in which the head, back, 

 and belly are covered with bony 

 plates, but the rest of the body is 

 naked. This bony armour gives 

 the fish something of the appear- 

 ance of the Ostracoderms, with 

 which group it is often, though 

 erroneously, classified. The back- 

 bone is represented by an unseg- 

 mented rod (the notochord, N, 

 Fig. 143), to which arches of bone 

 are attached (TV, H, Fig. 143). 

 Paired ventral fins were present, 

 but pectorals have not been found. 

 The jaws were provided with teeth, 

 which fuse into plates. In the 

 uppermost Devonian of Qhio are 

 found some huge fishes allied to 

 Coccosteus, but much larger and 

 more formidable. The most im- 

 portant of these are Dinichthys 

 and Titanichthys, the latter at- 

 taining a length of 25 feet. 



A higher type of Devonian fish 

 is that of the Crossop/erygii, an 



