PEDIGREES. 183 



have already remarked, were armoured fishes, 

 which increased in wealth of form till they 

 reached the climax of their evolution in the 

 Carboniferous and Permian periods. By this 

 time they had flowered out into a very numerous 

 company, in which we may distinguish two types 

 an elongated, and a deep-bodied. Above the 

 Permian, remains of the deep -bodied form 

 gradually dies out, finally disappearing towards 

 the end of the Jurassic period. Although these 

 deep-bodied fishes held their own for an enor- 

 mous period of time, they yet have a shorter 

 record than the parent stock. This, during the 

 lower Carboniferous period, produced a very re- 

 markable scaleless form, known as Phanerosteon ; 

 and during the Jurassic an equally remarkable 

 type, characterised by deeply overlapping scales, 

 ornamented with tubercles of the glistening 

 ganoine. Finally, as we have already remarked, 

 we may reckon as descendants of the earliest 

 forms our modern sturgeons, which again afford 

 us valuable material for our evolutionary studies 

 in the highly specialised shovel-beaked, and the 

 more typical sturgeon, which we can trace back 

 to the Lias, in the form of Chondrosteus. 



From the sturgeons we must pass to the con- 

 sideration of a fish which, until recently, was a 

 stumbling-block to many. This is an American 

 fish (Amia calva) 9 commonly known as the bow- 

 fin, but also as the mud-fish, lawyer-fish, and 

 Joseph Grindle. For a long while this fish was 

 believed to be closely allied to the herrings, it 

 was only after a closer acquaintance of its 

 anatomy was made that its real affinities became 



