File:The alligator and its allies (1915) (14801161873).jpg

Identifier: alligatoritsall00reesuoft (find matches)
Title: The alligator and its allies
Year: 1915 (1910s)
Authors: Reese, A. M. (Albert Moore), b. 1872
Subjects: Alligators
Publisher: New York : G.P. Putnam's Sons
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: MSN

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thers he had taken sixteen or twenty lesser.None regards them much there, whatever Monar-des relateth. CHAPTER II THE SKELETON A. The Exoskeleton THE exoskeleton is well developed in theCrocodilia, and forms a very considerableprotection to its bearer. It is both dermaland epidermal in origin. The epidermal skeleton of the alligator consists ofoblong horny scales, arranged in transverse rows;the long axes of the scales are parallel to that of thebody. On the tail, except along the mid-dorsalline, and on the ventral side of the trunk and headthese scales are very regular in outline and arrange-ment; on the sides of the head and trunk and onthe legs they are much smaller and less regularlyarranged, while along the mid-dorsal line of thetail, especially in its posterior half, they are ele-vated into tall keels that give the tail a largesurface for swimming. The first three digits ofboth manus and pes are armed with horny claws,which also belong to the epidermal part of theexoskeleton. 46
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Fig. 15. Alligator Skins; Under-surface and Horn-back. The Skeleton 47 The dermal exoskeleton consists of bony scutesthat underHe the epidermal scales of the dorsal sur-face of the trunk and anterior part of the tail. Theoverlying scales, except in very young animals,are always rubbed off, so that the bony scalesare exposed. The ventral or inner surface of thescutes is flat, while the outer surface is stronglykeeled and in old animals is often rough and pit-ted. The plates are nearly square in outline andare closely joined together in most places. The scutes are grouped in two fairly distinctareas known as the nuchal and the dorsal shields.The former lies just back of the head, in the regionof the fore legs, and consists of four larger and anumber of smaller plates (Fig. 15). The latter, ordorsal shield, extends over the back in fairly regularlongitudinal rows and quite regular transverserows. At the widest part of the trunk there aresix or eight of these scutes in one transverse row.

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