FREE APPENDAGES — TETRAPODA 277 



In man some of the typical (and primitive) bones of the basipodium have 

 fused, and names are employed for all which differ from those of comparative 

 anatomy, although sometimes used for lower groups, confusion resulting. Some 

 of these names are common in older works and are given here, the less preferable 

 in parentheses. 



In the hand the navicular (scaphoid) is formed of radiale and usually a 

 centrale, the latter sometimes remaining separate. The lunatum (semilunar) 

 is the intermedium, the triquetrum (pyramidalis) the ulnare. Carpalia i and 2 

 are respectively multangulvun majus (trapezixun) and multanguliim minus 

 (trapezoid) ; carpale 3 is the capitatiun while carpalia 4 and 5 fuse as the hamatum 

 (tmcinatum). In the foot tibiale and intermedium form the talus (astragalus) 

 and when the centrale unites with the talus, the compound bone is the tritibiale. 

 The fibulare is the calcaneum (os calcis). The first three tarsalia are the first, 

 second and third cvmeiformia, tarsalia 4 and 5 fusing as the cuboid bone. 



The typical number of metacarpals and metatarsals is live, these 

 being distinguished by number as are the digits. The thumb has the 

 special name of pollex, the great toe is the hallux. None of the 

 other digits of the foot have special names, the second of the hand is 

 the index, the fourth the annulus and the fifth the minimus. 



All of these bones of the appendages are preformed in cartilage. 

 There may be others, some cartilage, some (sesamoid) ossifying 

 directly in tendons or other connective tissue. ' Some of the additional 

 cartilage bones are often interpreted as indications of additional 

 digits — a prepollex or a prehallux (fig. 303), on the inner side of the 

 hand or foot, a postminimus on the outer, most common in Amphibia 

 and mammals. The hind limb often has an ossification, the patella 

 (knee cap) in the extensor tendon which passes over the knee; a 

 similar brachial patella is rare in the elbow. The pisiforme is a 

 small bone on the ulnar side of the carpus of many mammals 

 and some reptiles. It is said by some to have a membranous 

 origin, by others that it arises in cartilage and is the remnant of a 

 postminimal digit. 



In the simpler Tetrapoda (Stegocephals, Urodeles) the limbs 

 extend at right angles to the body axis, are bent downwards at elbow 

 and knee, and at ankle and wrist they become horizontal, the 

 digits pointing forwards and laterally. In higher Tetrapoda the 

 stylopodia are normally parallel to the body axis, the humerus point- 

 ing backwards, the femur forwards. Without other modifications this 

 would result in the digits of the hand pointing backwards; but there 

 has been a torsion of the hmb involving, first, the brachium (clearly 



