The =tarsus=. The tarsal bones of the Turtle do not retain their primitive arrangement to such an extent as do the carpals. They are arranged in a proximal row of two and a distal row of four. Of the bones in the proximal row the postaxial one is much the smaller and is the =fibulare=; the larger pre-axial one (fig. 40, B, 15) represents the =tibiale=, =intermedium=, and =centrale= fused, and articulates with both tibia and fibula. The first three distal tarsalia are all small bones and are very similar in size, and each articulates regularly with the corresponding metatarsal. The fourth bone (fig. 40, B, 19) is much larger, and represents tarsalia 4 and 5 fused. The first two distal tarsalia articulate with the pre-axial tarsal of the proximal row, the third only with its neighbours the second, and the fused fourth and fifth. The latter articulates with both bones of the proximal row. Each =digit= consists of a metatarsal and of a varying number of phalanges. The =metatarsals=. The first metatarsal (fig. 40, B, 20) is broad and flattened, the second, third and fourth, are all elongated bones with nearly flat terminations formed by small epiphyses. The fifth is large and flattened, and the articular surface for the phalanx is situated somewhat laterally. The =phalanges=. The first digit has two phalanges and is the stoutest of them all; its distal phalanx is sheathed in a large horny claw. The other digits, of which the third is the longest, have each three phalanges. The distal phalanges of the second and third digits are flattened and pointed and bear small horny claws. FOOTNOTES: [89] Another view commonly held is that the neural and costal plates are respectively formed by the expanded neural arches and ribs. CHAPTER XV. THE SKELETON OF THE CROCODILE. The species chosen for description is _C. palustris_, a form occurring throughout the Oriental region, but the description would apply almost equally well to any of the other species of the genus _Crocodilus_, and with comparatively unimportant modifications to any of the living Crocodilia. I. EXOSKELETON. The exoskeleton of the Crocodile is strongly developed and includes elements of both epidermal and dermal origin. _a._ The =epidermal exoskeleton= is formed of a number of horny =scales= or plates of variable size covering the whole surface of the body. Those covering the dorsal and ventral surfaces are oblong in shape, and are arranged in regular rows running transversely across the body. The scales covering the limbs and head are mostly smaller and less regularly arranged, and are frequently raised into a more or less obvious keel. Those covering the dorsal surface of the tail are very prominently keeled. The epidermal exoskeleton also includes the horny =claws= borne by the first three digits of both manus and pes.