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DESCRIPTION OF A SECOND GANOID PISH FROM 

 THE LOWER MESOZOIC SANDSTONES NEAR 

 TINDER-BOX BAY. 



By Messes. R. M. Johnston and A. Morton. 



On the 19th August, 1889, we had the pleasure of bringing 

 under the notice of the members of this Society a new Ganoid 

 Pish, from the Knocklofty sandstones, and named Acrolepis 

 Hamiltoni, in honour of our worthy President, Sir Robert 

 Hamilton. We have now the honour of giving a full 

 description of a second species of the same genus recently 

 discovered in a sandstone formation near Tinder-Box Bay, 

 deemed to be nearly of the same geological horizon as the 

 sandstones of Knocklofty. 



Acrolepis Tasmanicus. n. sp. Johnston and Morton. 



Body compressed, elongate, elliptical ; length from snout 

 to end of caudal fin, nearly 6 inches ; length of head, 141ines; 

 length of body, 4| inches ; snout projecting beyond lower 

 jaw ; greatest depth, 14 lines ; least depth at peduncle, 5 lines. 

 Dorsal fin somewhat falcate, composed of 48 to SO slender 

 rays (6 to a line) each one of which branches into two or 

 three sub-divisions near extremities, and each one or two 

 rays crossed distantly and in a curved manner by fine oblique 

 ridges; base, 8| lines long, occupying a position nearer the 

 tail than the snout, anterior end being 37 lines distant from 

 snout, and the posterior end 45| lines; greatest length of 

 dorsal (2nd, 3rd and 4th longest) same as base, 8| lines ; 

 the longer anterior rays curve over the anterior ones, which 

 abruptly diminish in size, the posterior margin being thus 

 irregularly vertical. Anal fin about the same size and com- 

 posed of nearly the same number of rays as the dorsal fin, 

 but its position is nearer the tail, the anterior portion com- 

 mencing about 40 lines from the snout, and the posterior 

 terminating about 48f lines distant. Ventral fin composed 

 of about 18 fine rays, central, and well in advance of anal fin. 

 Pectoral, imperfect, somewhat elongate, and consisting of 

 numerous fine rays, which become subdivided towards 

 extremities as in the dorsal fin. Rays of sub-caudal fin 

 numerous, fine ; fin elongate, nearly equal in length to the 

 slightly elevated caudal extremity,* and forming with it a 



* Length of caudal lobe (upper), 19 lines; length of sub-caudal fin, 14 lines; 

 distance between extreme tips of caudal furcation, IS) lines. 



