310 ON THE DERMAL ARMOUR OF JACARE AND CAIMAN 
arranged) very beautifully ; and a young /acare of about 18 inches in 
length, for which Iam indebted to the kindness of the same gentle- 
man, proves that the scutes are developed even in specimens of this. 
age. I have no hesitation therefore in expressing my belief that this 
singularly complete dermal armour will be found to be characteristic 
of all the species of the genera Cazman and /acare. On the other 
hand, I have examined A/égator Mississipiensis, Crocodilus vulgaris,. 
C. biporcatus, C. Americanus, C. rhombifer, and C. bombifrons, Mects- 
tops cataphractus, and Gavialis Gangeticus, of various ages and sizes, 
without having been able to discover a trace of ventral scutes.. This 
is the more remarkable, as the well-marked ventral and dorsal shields 
of many of the ancient Zv/eosauria would lead one to expect a corre-- 
sponding exoskeleton (if anywhere) in their nearest allies, the modern 
Gavialide. However, Goniopholts, with its strong armour, is more like: 
an ordinary Crocodile; and I have recently discovered that a true 
Crocodile in some respects curiously similar to C. dombifrons (C. Has- 
Ziuesi@) was covered with scutes exceedingly like those of the modern 
Caiman and Jacare. ‘ 
In minute structure the bony scutes of /acare closely resemble 
those of such a fish as a Sturgeon: a middle layer, containing so 
many canals as to appear almost cancellated in longitudinal or trans- 
verse section, is covered externally by a thin, and internally by a 
thick, layer composed of bony lamellz, nearly parallel to the plane 
of the scute. Round the canals of the middle layer, the bony lamelle. 
are disposea concentrically, to a greater or less extent. The lacunze 
are of very various shapes; and there are perhaps as many short as 
elongated forms. The canals of the middle layer communicate by 
large branches with the inner, by smaller and fewer branches with 
the outer surface of the scute. 
In. the young /acare mentioned above, I found the dermis to be 
cistinguishable into two layers. The more superficial of these is thin,. 
made up of irregular or formless connective tissue, and contains many 
ramified pigment-masses. Its smooth outer surface underlies the rete. 
mucosum. Internally, it passes into the second or deep layer, which 
consists of successive layers of distinctly fibrous connective tissue, 
disposed in definite parallel bundles, and having a very regular 
arrangement. Throughout a space corresponding with the area of 
each scale, in fact, the bundles of each layer cross those of the suce, 
ceeding layer at right angles ; and the successive tiers of bundles are. 
tied together by short cords disposed perpendicularly to the planes of 
the tiers. A corresponding arrangement of the bundles of connective: 
tissue has long been known to obtain in the dermis of Fishes and, 
