THE OLD RED SANDSTONE. 159 
handle, and the large and thickly clustered fins the spreading 
bristles.* 
Some of the occipital bones of the Holoptychius are very 
curious and very puzzling. There are pieces rounded at one 
of the ends, somewhat in the manner of the neck joints of 
our better known quadrupeds, and which have been mistaken 
for vertebree; but which present evidently, at the apparent 
joint, the enamel peculiar to the outer surface of all the plates 
and scales of the creature, and which belonged, it is proba- 
ble, to the snout. There are saddle-shaped bones, too, which 
have been regarded as the central occipital plates of a new 
species of Coccosteus, but whose style of confluent tubercle 
belongs evidently to the Holoptychius. The jaws are exceed- 
ingly curious. They are composed of as solid bone as we 
usually find in the jaws of mammalia; and the outer surface, 
which is covered in animals of commoner structure with por- 
tions of the facial integuments, we find polished and japanned, 
and fretted into tubercles. The jaws of the creature, like 
those of the Osteolepis of the lower formation, were naked 
jaws ; it is, indeed, more than probable that all its real bones 
were so, and that the internal skeleton was cartilaginous. A row 
of thickly-set, pointed teeth ran along the japanned edges of 
the rnouth — what, in fish of the ordinary construction, would 
be the lips; and inside this row there was a second and 
widely-set row of at least twenty times the bulk of the other, 
and which stood up over and beyond it, like spires in a city 
over the rows of lower buildings in front. A nearly similar 
disposition of teeth seems also to have characterized the 
* There are now six species of Holoptychius enumerated — H. An- 
dersoni, H. Flemingii, H. giganteus, H. Murchisoni, H. nobilissimus, 
and H. Omaliusii. 
