306 ON THE DERMAL ARMOUR OF JACARE AND CAIMAN 
which corresponds with the external ridge, under which the sides of 
the scute seem to meet in an angle. This may be called the ‘ angu- 
lation” of the scute. From before backwards, the inner surface of the 
‘scute is a little convex. The scute is thickest in the middle ; pos- 
teriorly, it thins off to an edge and overlaps its successor; anteriorly, 
its outer surface is bevelled off at an acute angle with the inner, so as 
to give rise to a smooth shelving surface—wide from side to side, 
narrow from before backwards—forming the “ articular facet,” which 
is overlapped by the inner surface of the posterior edge of the pre- 
ceding scute. I have termed this the “articular facet ;” but it must 
not be supposed that there is anything like a true joint between 
the opposed facets of the overlapping and overlapped scutes; on 
the contrary they are at once separated and connected by the 
dermal connective tissue. 
The posterior margin of the articular facet is separated by a deep 
transverse groove, divided by little partitions into as many pits, from 
the rest of the sculptured surface; but there is no trace of any suture 
dividing the scute into two portions. The lateral margins of each 
scute are united by serrated sutural edges with those which lie 
next to them in the same transverse row; so that each row forms a 
nearly solid flat bony bar, composed, in the middle of the back, of as 
many as ten distinct scutes. The outer edges of the outermost scutes 
only, thin off and exhibit no sutural serration, inasmuch as they are 
not directly connected with any other scutes. 
The median line of the back corresponds in general with the 
‘suture between the two middle scutes of each transverse row ; so that 
the scutes are disposed symmetrically on either side of that line. 
Furthermore, the anterior part of the inner surface of each of the two 
middle scutes is connected by ligament with the extremity of the 
spinous process of a vertebra; at least, this is the case in the dorsal, 
lumbar, sacral, and anterior caudal regions. 
The scutes which protect the vexzral side of the body, from the 
throat backwards, are four-sided and similar in their ornamentation to 
the dorsal scutes; but they exhibit neither ridge nor angulation, their 
outer and inner surfaces being parallel, and either nearly flat or evenly 
curved. Each forms, in fact, a segment of a large cylinder, inasmuch 
as the whole ventral shield is convex transversely, being nearly flat in 
the middle and much bent up at the sides. The dorsal shield, taken 
as a whole, is, on the contrary, nearly flat. The lateral edges of the 
ventral scutes interlock suturally ; and their anterior and posterior 
edges are overlapped and overlap, just like the dorsal scutes. The 
