1905.] ANATOMY OF THE LEATHERY TURTLE. 313 



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. 



h (deep). Inserted upon the tibial side of the heeh 



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 Y. 



Extensor h^evis II.-IV. + Extensor hallucis j^ro-prius (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., lY. 



Flexores breves (text-figs, 65 & 66. 23). — Five small muscles 

 inserted upon the base of the first phalanges of digits I., II., 

 III., lY. 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 tai-sus. 

 iii. From the fibular margin of the tarsus. 

 iv. From the head of metatarsus Y. 



There is no interosseics cruris, which in Ghelone is a very strong 

 muscle. 



Eye. 



The eyelids (text-fig. 68) have the same general form and 

 structure as those of Ghelone. Their inner surface, and moi-e 

 especially that of the nictitating membi-ane, is deeply pleated. 

 The pleats, or rather lamina?, lie close togethei- 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. 



