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Show 1 9 0 5 . ] ANATOMY OF THE LEATHERY TURTLE. 3 1 3 Towards its distal end the muscle divides in two fairly distinct sheets a (superficial). Giving off four rounded tendons inserted respectively into the distal parts of the four inner toes. The tendons towards their ends blend with the periosteum so that their exact point of insertion is not definite. b (deep). Inserted upon the tibial side of the heel. The superficial part is the deep flexor proper, the deeper layer is Gadow's tibialis posticus. Two small slips, to which I can find no reference, pass from the surface of the deep flexor (just above the ankle) to the base of metatarsus V. Extensor brevis II,-IV. -f- Extensor hallucis proprius (text-fig. 67. 22).-Origin : from the inner border of the shaft of the fibula and extensor surface of the tarsus in a line with digit III., and from the extensor surface of metatarsals I., II., III., IV. Insertion : by tendons that gradually fuse with the periosteum to the terminal phalanges of digits I., II., III., IV. Flexores breves (text-figs. 65 & 66. 23).- Five small muscles inserted upon the base of the first phalanges of digits I., II., III., IV. Origin :-■ i. From the radial side of the tarsus, it is partly fused with the deep flexor. ii. By two heads, one from the head of metatarsus II., the other from the fibular margin of the tarsus. iii. From the fibular margin of the tarsus. iv. From the head of metatarsus V. There is no interosseus cruris, which in Chelone is a very strong muscle. E y e . The eyelids (text-fig. 68) have the same general form and structure as those of Chelone. Their inner surface, and more especially that of the nictitating membrane, is deeply pleated. The pleats, or rather laminae, lie close together like the leaves of a book and run approximately parallel to the margins of the lids. The basal parts of each lamina are the seat of smaller secondary pleats. •In Chelone there is a somewhat similar but relatively extremely feeble pleating of the conjunctival surface of the lids, and in this case the epithelium that covers the ridges consists almost entirely of mucous cells. It seems probable that in Dermochelys also the object of the pleating is to extend the mucous secreting surface. The contents of the orbits were decayed, with the exception of the bulbus oculi, but a large mass of granular greasy debris was most probably the remains of an enormous lacrymal gland such as that found in Chelone. The globe of the eye measures 55 mm. |