FINS OF &ANOIDS AND TELEOSTS. 565 



Posterior Dorsal Jin. — In this fin there are fifteea radial 

 elements all of which consist of a proximal segment, with a well- 

 marked postero-superior process, and a simple cubical distal 

 segment, with no trace of a hooked process. The fifteen fin-rays 

 are all soft and multiarticulate, and their cleft basal extremities 

 simply embrace the distal segments. 



Anal Jin. — In this fin there are nine radial elements and eleven 

 fin-rays, of vvhich two are spinose and the remainder soft. With 

 the possible exception of the first, all the radial elements are 

 bisegmental, and similar, both in structure and in their mode of 

 articulation with the fin-rays, to those of the posterior dorsal 

 fin. All the proximal segments, except the first, have well- 

 developed postero-inferior processes. The first element has no 

 distinct distal segment, but it is nevertheless possible that the 

 bony loop which grows backwards from the hinder margin of the 

 distal end of its proximal segment, and fuses with the contiguous 

 extremity of the second proximal segment, may, as in the anterior 

 dorsal fin, represent a fused distal segment. The first spine has 

 a " chain-link " articulation with the proximal segment of the 

 first radial element ; the second a similar articulation with the 

 bony loop between the proximal segments of the first and 

 second elements ; while the remaining soft rays clip the distal 

 segments of their respective radial elements, the last two rays, 

 however, being supported by the same distal segment. 



Mesoprion gemhra. 



Dorsal Jin. — Although a continuous structure, the dorsal fin 

 consists of an anterior spinose portion and a posterior section 

 composed of soft multiarticulate rays. The spinose portion con- 

 sists of ten spines supported basally by a series of eight biseg- 

 mental (PI. XXII. fig. 2Ji, r.e}-r.e.*) radial elements, all of which, 

 including the first, have distinct hooked distal segments. Both 

 in structure and in their articular relations to the spinose fin- 

 rays, the radial elements are similar to the corresponding elements 

 in Perca, except that neither the postero-superior processes of 

 the proximal segments uor the distal segments develop lateral 

 wing-like outgrowths, and hence there is no obvious bony groove 

 for the defiected spines. 



In addition to its normal spine, the third, the first radial 

 element supports two additional spines, viz., the first and second, 

 which are connected with the anterior portion of the distal end 



