THE OLD RED SANDSTONE. 53 
I] am acquainted with four species of Coccosteus — C. deci- 
piens, C. cuspidatus, C. oblongus, and a variety not yet named ; 
and many more species may yet be discovered.* Of all the 
existences of the formation, this curious fish seems to have 
been one of the most abundant. Ina few square yards of 
rock J have laid open portions of the remains of a dozen dif- 
ferent individuals belonging to two of the four species, the C. 
decipiens and C. cuspidatus, in the course of a single evening 
None of the other kinds have yet been found at Cromarty 
These two differed from each other in the proportions which 
their general bulk bore to their length — slightly, too, in the 
arrangement of their occipital plates. The Coccosteus latus, 
as the name implies, must have been by much a massier fish 
than the other; and we find the arch-like form of the plates 
which covered its head more complete : the plate representing 
the keystone rests on the saddle-shaped plate in the centre, 
and the plates representing the spring stones of the arch exhibit 
a broader base. The accompanying print (Plate III.) repre- 
ents the Coccosteus cuspidatus. ‘The average length of the 
creature, including the tail, as shown in most of the Cromarty 
specimens, somewhat exceeded a foot. A few detached 
plates from Orkney, in the collection of Dr. Traill, must 
have belonged to an individual of fully twice that length. 
* A fifth species has been named C. maximus. + See Note C. 
which still solicits inquiry as not yet definitely accounted for. The 
matter of fact in the case is certainly one which should be determined, 
not analogically, but onits own proper evidence, as furnished by good 
specimens. As for the remark regarding the probable position of the 
creature’s jaws, it was ventured on at first, as the reader may perceive, 
with much hesitation, and must now be regarded as more doubtful 
