MESIAL FINS OF GANOIDS AND TELEOSTS. 569 



Anal Jin. — The anterior division of" the anal fin consists of 

 twelve bisegmental radial elements, supporting thirteen fin-rays. 

 The first element supports two spinose rays, the first by a 

 " chain-link " articulation with the distal end of its proximal 

 segment, and the second by an articulation with the hooked 

 distal segment, in conjunction with a facet on the proximal 

 segment of the second radial element. Tiie remainder support - 

 soft rays in the ordinary way. The relations of the six radial 

 elements supporting the six isolated finlets to one another and 

 to those of the anterior part of the anal fin are precisely as iu 

 the dorsal fin. 



Carangid^, 



Caranx georgianus. 



Apart from variations in the number of radial elements and 

 fin-rays and other minor differences, the dorsal and anal fins of 

 Caranx are essentially similar to those of the mure typical 

 Acanthopterygii, such as Perca and PageMus. 



Sphtr^nid^. 



Sphyrcena Commersonii. 



This Teleost is interesting as aflording a transition from the 

 more typical Acanthopter\ gii previously described to such families 

 as the Cottidse and Mugilidse, in which more or fewer of the 

 radial elements of the dorsal fin become unisegmental by the loss 

 of their distal segments. 



Anterior Dorsal fin. — The short anterior dor.sal fin of this 

 species consists of five radial elements (PI. XXII. fig. 27) and an 

 equal number of spinose ra^'s. All the radial elements, except 

 the last, are bisegmental, and the postero-superior processes of 

 their proximal segments in conjunction wath the distal segments 

 form sections of a shallow medio-dorsal bony groove, as in many 

 of the preceding types. None of the distal segments are 

 hooked, and the method by which the fin-rays are supported is 

 very unlike anything hitherto described. All the spines are 

 furnished with imperforate bases terminating in a transversely 

 elongated condyle. The first spine (sp.r.) articulates with a groove 

 on the distal end of the proximal segment of the first radial 

 element, but with all the remaining spines (figs. 27 and 28) the 

 groove (g) for the reception of the condyle is formed by the distal 



