3°4 



A CTINOP TER \ 'Gil 



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 Y-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. 218). 

 Usually the scales have 

 peg and socket articula- 

 tions, and the peg often 

 appears as the continua- 

 tion of an inner thickei.ed ride;e. 



caudal. Those cases in which there 



But these scales, like the 



