14 URODELA CHAP. 



All the trunk -vertebrae, with the exception of the atlas, 

 carry ribs, at least vestiges thereof. Owing to the early dis- 

 appearance of the basiventral cartilages the capitular portions of 



the ribs are much reduced, and 

 are mostly represented by strands 

 of connective tissue only. The 

 ribs develop therefore occasion- 

 ally at some distance from the 

 vertebral column, and that por- 

 tion of the rib which in the 

 metamorphosed young newt looks 

 like the capitulum is to a great 

 extent really its tuberculum. 



FIG. 2. Transverse section through a Witness the position of the ver- 

 truuk- vertebra of a larva of Sala- tebral arter y, which still indi- 

 nuindra maculosa, enlarged. The right 



side shows the actually existing state, cates the true foramen trans- 



The homologies of 



bable original condition. A, Verte- these parts are Still more ob- 



!l^:^^S5 sired by the fact that a new 



cartilage ; Ch, chorda dorsalis ; Sp.c, process grows Out from the rib, 

 spinal canal ; *, the false transverse , 1-1-1 i A 



canai. by which the latter gains a new 



support upon a knob of the 



neural arch. Thus an additional foramen is formed, sometimes 

 confounded with the true transverse canal. The meaning which 

 underlies all these modifications is the broadening of the body, 

 the ribs shifting their originally more ventral support towards 

 the dorsal side. The whole process is intensified in the Anura ; 

 it is an initial stage of the notocentrous type of vertebrae. The 

 transverse ossified processes of the adult are often much longer 

 than the vestiges of the ribs themselves, and are somewhat com- 

 plicated structures. They are composed first of the rib-bearing 

 cartilaginous outgrowths of the neural arches ; secondly, of a broad 

 string of connective tissue which extends from the ventro-lateral 

 corner of the perichordal skeletogenous layer to the ribs. 



The shoulder-girdle is extremely simple. It remains almost 

 entirely cartilaginous, and the three constituent elements are not 

 separated by sutures. Ossification is restricted to the base of the 

 shaft of the scapula, and may extend thence over the glenoid 

 cavity. The coracoids are broad, loosely overlap each other, and 

 are " tenon and mortised " into the triangular or lozenge-shaped 



