A CTINOPTER YGII 



dorsal separate from the 

 appear to be two or more 

 dorsals (Teleostei, p. 480) 

 are probably due to 

 secondary modification. 

 In all the more primitive 

 groups fulcral scales are 

 found on the extreme 

 anterior edge of some or 

 all of the fins, especially 

 on the dorsal edge of the 

 caudal. The fulcra are 

 quite peculiar to this 

 Division, and consist of 

 a double series of elon- 

 gated scales (Fig. 286) ; 

 often the opposing scales 

 fuse to V-shaped fulcra 

 (Fig. 280). In the gular 

 series of plates the most 

 anterior median is gener- 

 ally large and the paired 

 series become very numer- 

 ous and narrowed (Figs. 

 285-7). They are con- 

 verted into freely movable 

 branchiostegal rays. The 

 two foremost may be 

 longer than the others, 

 but never occupy the 

 space between the two 

 rami as in the Osteo- 

 lepidoti, Coelacanthini, 

 and Polypterini, and are 

 probably not homologous 

 with the paired gulars of 

 the first two Orders. The 

 body -scales and dermal 

 plates of the more primi- 

 tive forms are of the true 

 ganoid structure (p. 2 1 8). 

 Usually the scales have 

 peg and socket articula- 

 tions, and the peg often 

 appears as the continua- 

 tion of an inner thicker. ed 



caudal. Those cases in which there 



-S3 



i! 



ridge. But these scales, like 



ns 

 the 



