370 Messrs. Hancock & Atthey on Reptile- and Fish-Remains 



triangular "bone supported, directly or indirectly, the great 

 pectoral spines. 



There are found also frequently associated with the remains 

 of Oyracanthus large thin layers or patches of matter, almost 

 entirely composed of minute compressed bodies, of which 

 there are two kinds. One, much smaller than the other, and 

 by far the more numerous, is upwards of one-twentieth of an 

 inch high and not quite so broad ; it has usually two, some- 

 times three, conical, recurved, diverging points rising from an 

 expanded base. The large kind is usually one-tenth of an 

 inch high, and is somewhat wider at the base ; it is sometimes 

 a little larger, but more frequently much smaller. It is much 

 compressed, and the base is considerably widened ; the upper 

 margin is divided into from four to seven much recurved 

 conical denticles, which are sharp-pointed, and have fom* or five 

 stout longitudinal ridges on the arched or dorsal surface. Several 

 large patches of these bodies have occurred, one of which mea- 

 sures twenty inches by fifteen inches. It is therefore pretty 

 clear that they cannot be teeth, which are not usually found 

 together in such vast multitudes ; they are much more likely 

 to be dermal tubercles, and these patches to be the remains of 

 the skin of Gyracantims. It should also be mentioned that 

 Cladodus mirabilis has occurred three or four times at News- 

 ham, and always associated with these dermal patches. May 

 it not, therefore, prove to be the tooth of Oyracanthus ? 



Note. — Mitrodus quadricornis of Prof. Owen (pi. 3) is un- 

 doubtedly nothing more than the larger kind of these dermal 

 tubercles. In size, proportion, and form it agrees exactly with 

 them ; and in the minute structure there is no difference what- 

 ever, as is demonstrated by the numerous sections of them 

 which we have had the advantage of examining. This 

 ^* minnow," then, of our shales is found to be identical with 

 Oyracanthus tuberculatus, perhaps the largest fish of the coal- 

 measures. 



In the figure of Mitrodus only a small portion of the den- 

 ticles is shown ; the points, being strongly recurved, are neces- 

 sarily cut away in such a section as that represented. It is 

 only the base of the toothlets that Prof. Owen has seen ; and 

 consequently his knowledge of the true form must be very 

 imperfect. The angles represented at the margin of the den- 

 ticles indicate the external ridges described above. 



Diplodus gihhosus, Agassiz. 



This is a common fossil at Newsham and Cramlington, and 

 is usually found in connexion with a thick granular layer of 



