AQUATIC ANIMALS OP THE COAL. 211 



 a fine species of Diplodus, which appears to be new, and which I 

 have named D. acinaces. Its lateral denticles are compressed and 

 ■harp-edged, but scarcely cremdated, and both bent in the same 

 direction. Middle cone obsolete ; base large and broad. One denticle 

 is usually much larger than the other. The greatest diameter of the 

 larger denticle is to its length as one to three. A tooth of ordinary 

 size measures six lines from the lower side of the base to the point of 

 the longest denticle, and the base is four lines broad (Fig. 58). I 

 regard as probably belonging to this fish certain cylindrical spines 

 found in the same bed. They are about half an inch in diameter, with 

 marly central canal two lines in diameter, and are marked externally 

 with parallel longitudinal striae. 



Among fossils from Pictou forwarded to me by Mr Poole, there is 

 a new Diplodus (D. penetrans), Fig. 57. This is smaller than D. 

 acinaces of the Main Coal. Its height is about 

 two and a half lines, and the breadth nearly the Fig. 57. Fig. 58. 

 same. The lateral points are half as broad as 

 long, and flattened ; rhombic in cross section at 

 the base ; serrated, especially at the outer and 

 lower margins. They diverge at an angle of 

 35° to 40°, and the central denticle is small and „ , ,...,_, 



' M Teeth of Diplodus. 



conical. The base is broad and strongly lobed. 



These teeth occur in the roof of beds of coal near to and above the 



New Glasgow conglomerate, and in the roof of the Main Coal.* 



In the same collection is a small tooth of Ctenoptychius with eight 

 denticles; — the specimen is an imperfect impression. There are also 

 remains of several ganoid fishes. One of these is a conical curved 

 tooth, half an inch long, smooth on the convex side, and marked on 

 the concave side with five spiral ridges. It probably belongs to the 

 genus RJdzodus. With it are scales, possibly of the same fish, which 

 have the punctures and stria; of the genus Osteoplax of M'Coy. There 

 are also two remarkable flattened sabre-shaped spines, one inch and a 

 half in length, and resembling in general form the Devonian MacJiaTa- 

 ranthns. Several rounded scales have the characters of those of 

 Ithizodus, and there are numerous scales and other remains referable 

 to Palaoniscus and allied genera. These last in the Albion measures, 

 as at the Joggins, abound in the bituminous shales and thin coals. 



Notwithstanding the abundance of these remains of fishes, their 



dislocated condition opposes great obstacles to their satisfactory study. 



They all occur in the same beds, usually rich in vegetable matter, 



which contain the shells of Naiadites and the Cythcrc and Spirorbis. 



* These species were described in " Supplementary Chapter," 1860. 



