100 ON THE STAGONOLEPIS ROBERTSONI AND THE 
sculptured to the smooth surface was far less in these than in the 
wide scutes. 
I have compared the parts which have just been described with 
the scales of Glyptopomus ; and, though there is a certain resemblance 
between the latter and the flat scutes, the dermal plates of no fish 
with which I am acquainted present any similarity to the angulated 
and thick scutes. On the other hand, any one acquainted with the 
characters of the exoskeleton in the Crocodilian Reptiles can hardly 
fail to have his attention arrested by the remarkably similar features 
of the scutes of Svtagonolepis; and close investigation shows that 
there is not a single peculiarity of the latter which may not at once 
be paralleled by those of Crocodilian scutes. To begin with the 
sculpture or ornamentation,—the outer surface of the scutes exhibits 
distinct rounded pits, so disposed as to appear to radiate more or 
less distinctly from a common centre, not only in the modern Croco- 
diles, but in the Eocene Crocodilus Hastingsie and in the Mesozoic 
Teleosauria. Wherever these scutes possess a median ridge, the 
centre of radiation of the pits is somewhere on that ridge, and the 
highest part of the ridge is devoid of sculpture. Next, in respect 
of their form—the variously-shaped scutes of S¢agonolepis become 
readily intelligible when those of the existing and extinct Crocodiia 
are understood. To this end, however, I must here interpolate a 
brief disquisition upon the characters of the dermal armour in the 
Crocodilia in general,—a subject upon which I have not found it very 
easy to gain definite information. ° 
Dermal Scutes of Recent Crocodilia—So far as my present infor- 
mation goes, there are two modes of arrangement of the dermal 
armour among the Cvocodz/za—the one characteristic of the recent 
Crocodiles, the other known to exist in the Amphiccelian genera. 
In the recent Crocodi/ia there are numerous longitudinal series of 
dermal plates upon the dorsal region of the body. The large and 
regular scutes are divisible into three distinct sets: nuchal, cervical, 
and dorso-caudal. The scutes do not always overlap, and in the 
dorsal region there may be as many as ten regular and large scutes 
in a transverse row. Along the margins of the shield formed by the 
regular scutes small and irregular ones are scattered. 
The ventral armour varies greatly, no osseous plates at all being 
developed in this region in some recent Crocodilza, while in others | 
find the ventral shield to be very largely developed. 
In the Amphiccelian Crocodilza at any rate in the Zeleosauria, 
1 The scutes of the specimen of Gortophol?’s crassidens in the British Museum exhibit a 
narrow smooth articular facet along that edge which is produced into the peg; but Iam 
