PELVIS AND HIND-LIMB OF THE CROCODILE. 119 



lanx." In tlie crocodilia, the pollex has two phalanges, 

 the index three, the medius four, the annularis four, and 

 the minimus three. The terminal phalanges, which are 

 modified to support claws, are called " ungual" phalanges. 



As the above-described bones of the scapular extremity 

 are developments of the appendage of the scapular arch, 

 which is the haemal arch of the occipital vertebra, it 

 follows, that, like the branchiostegal rays and opercular 

 bones in fishes, they are essentially bones of the head. 

 But the enumeration of the bones of the crocodile's skull 

 is not completed by these ; there is a bone anterior to the 

 orbit, which is perforated -at its orbital border by the duct 

 of the lachrymal gland, whence it is termed the " lach- 

 rymal bone," and its facial part extends forwards between 

 the bones marked 14, 15, 21, and 26. In many croco- 

 dilia there is a bone at the upper border of the orbit, 

 which extends into the substance of the upper eyelid ; it 

 is called " superorbital." In the crocodilus palpebrosus 

 there are two of these ossicles. 



Both the lachrymal and superorbital bones answer to a 

 series of bones found commonly in fishes, and called 

 " suborbitals" and " superorbitals." The lachrymal is the 

 most anterior of the suborbital series, and is the largest 

 in fishes; it is also the most constant in the vertebrate 

 series, and is grooved or perforated by a mucous duct. 

 These ossicles appertain to the dermal or muco-dermal 

 system or " exoskeleton," not to the vertebral system or 

 " endoskeleton." 



There remains, to complete this sketch of the osteology 

 of the crocodile, a brief notice of the bones composing 

 the diverging appendage of the pelvic arch : these being 

 a repetition of the same element as the appendage of the 

 scapular arch, modified and developed for a similar ofiice, 



