OB OSSEOUS SYSTEM. ]\ 



surface of which shows it to be formed of the tibia and 

 fibula anchylosed together. To this succeeds a lengthened 

 astragulus and calcaneum (n,) then three very minute cunei- 

 form bones of the tarsus, and then the lengthened bones of 

 the meta- tarsus and the phalanges of the five toes (o.) The 

 humeri (A, A,) are comparatively short, strong, and slightly 

 bent ; the radius and the ulna (i, i,) are anchylosed like the 

 tibia and fibula, and the six small carpal bones (k, k,) are 

 succeeded by four long meta-carpal bones, the phalanges of 

 four fingers, and a small rudiment internally of a fifth. The 

 scapular apparatus (Fig. 35,) for the support of the arms 

 is here very complete, and also the sternum, although there 



are no ribs to reach it. The posterior 



,. ,\ f ., FIG. 35. 



curved portions (, t,) of the scapulae, 



are thin and cartilaginous, as in many 

 fishes and reptiles, and the anterior 

 parts (f)f y ) which chiefly contribute 

 to the formation of the glenoid cavity 

 (k, k,) for the head of the humerus is 

 strong, and ossified. From the gle- 

 noid cavity, on each side, proceeds inwards the coracoid 

 bone (e, e,) which expands as it reaches the sternum (d.) 

 Above the two coracoid bones, (e, e 9 ) are the two slender cla- 

 vicles (c, c,) which also proceed from the glenoid cavities to 

 the sternum, and leave a considerable vacant space between 

 them and the coracoid bones. The anterior (a,) and the 

 posterior (h,) portions of the sternum are thin, flexible, car- 

 tilaginous laminae, and the intermediate parts are ossified 

 and strong, for the insertion of muscles, the support of the 

 scapular arch, and the protection of the fore part of the 

 trunk. The upper thin portion (,) appears to consist of 

 the two epi-sternal pieces, the next part (b,) of the two hyo- 

 sternal elements, the next (d } ) the single ento-sternal, to 

 which both the clavicles and coracoid bones are attached ; 

 the next (t/ 9 ) the two hypo-sternal elements, and the inferior, 

 thin, cartilaginous, terminal piece (h,) the two united xiphi- 

 sternal elements which usually terminate this bone. 



The bones of the head, even in the highest of the caduci- 

 branchiate amphibia, are still as loosely united together as 

 in most of the osseous fishes, as is seen in the skull of the 

 common frog, rana esculenta, (Fig. 36.) The occipital bone 



