A rOSSIL FISH FEOM THE LIA.S. 295 



aseend almost at riglit angles into the upper lobe of the tail, 

 there are ossicles intermediate between the vertebrae and the fin- 

 rays. They are smaller in size than those of the lower lobe, and 

 extend not only from the ventral but also from the dorsal sur- 

 face of the vertebrae. The outer fin-rays, springing from the 

 extremity of the vertebral column, are the strongest and attain a 

 length of over 6 inches ; about 1"5 inch at the base is solid, the 

 remaining portion being composed of articulations, jointed at 

 very short intervals and divided repeatedly into divaricating 

 branches. The dorsal margin of the fin is strengthened by a 

 series of fulcral rays, much larger and stronger than those of the 

 lower lobe. They spring from the series of ossicles attached to 

 the neural surface of the vertebrae already mentioned, and form a 

 strong support to the long fin-rays extending from the termina- 

 tion of the bony axis of the body. The fulcral ray forming the 

 base of the series is 1"3 inch in length ; that portion of it im- 

 bedded in the integuments of the fish is divided into five prong- 

 like rootlets, the outermost nearly half an inch apart. The suc- 

 ceeding fulcra are longer and narrower ; and beyond these they 

 gradually decrease in size. The whole fin possesses characteristics 

 indicating great power combined with the utmost pliability. 



The dorsal and anal fins are supported by strong neural and 

 haemal spines attached to the vertebrae. Between these and the 

 fin-rays are, respectively, the interneural and interhaemal spines. 

 The interspinous bones supporting the dorsal fin are about 

 1"5 inch in length, pointed at the lower extremity, the upper one 

 enlarged and rounded, with a cup-like extremity, to form an 

 articulated base of attachment for the fin-rays. The latter are 

 round at the base, fitting to the interspinous bones ; the ray for 

 a length of 1"5 inch is undivided; it has a somewhat sigmoidal 

 curvature, and is about "15 inch in diameter. Between the prin- 

 cipal rays are others of the same length but much thinner. 

 Springing from the posterior surface of the base of one ray, they 

 approach, and appear to have been attached to, the upper anterior 

 extremity of the next. The upper extremity of the major fin -rays 

 is enlarged and immediately bifurcates, the bifurcations redividing 

 as in the caudal fin. The subdivisions of the fin-rays are jointed 

 in a similar manner to those of the caudal fin. The dorsal fin is 

 composed of 18 fin-rays besides the smaller intermediate ones, 

 and when perfect would be fully 6 inches in greatest altitude. 

 The anterior margin is strengthened by a series of imbricating 



