The SHOULDER-GIRDLE and "sternum" are more complete than in the Urodela, there being also a pair of clavicles, fused with the precoracoidal bars. The whole apparatus presents two types. In the arciferous type the coracoids and precoracoids retain a great amount of cartilage in their distal portions, and these cartilages (the epicoracoids of some authors) overlap each other movably on one another, the right usually lying ventrally upon the left. The epicoracoidal cartilage of each side, by connecting the distal end of the coracoid with the precoracoid of the same side, forms an arc, hence "arciferous." In the firmisternal type the epicoracoidal cartilages are much reduced, and, instead of overlapping, meet in the middle line and often fuse with each other, forming thereby a firm median bar, which connects the ventral ends of the precoracoids with those of the coracoids. This type is morphologically the higher and more recent, and passes in the larval stage through the arciferous condition. It is restricted to the Ranidae, Engystomatinae, and Aglossa. Although these two types afford an excellent distinctive character for the main divisions of the Anura, they are to a certain extent connected by intermediate forms in such a way, that, for instance, in _Bufo_ and among Cystignathidae in _Ceratophrys_, the two opposite epicoracoidal cartilages begin to unite at the anterior end. In many Engystomatinae the precoracoids together with the clavicles are much reduced, sometimes to thin ligaments, being in this case mostly curved back and lying closely against the coracoids; or they may be lost completely. Very rarely the precoracoidal bars are actually much stronger than the coracoids, {25}and the median symphysial bar of cartilage is lost; this is the case in _Hemisus_. The scapula is always large and curved into transverse, dorsally broadening blades, the dorsal greater portion of which, the so-called supra-scapula, does not ossify but calcifies. [Illustration: FIG. 5.–Ventral views of the shoulder-girdles of various Anura. (Slightly enlarged.) 1, _Bombinator igneus_, and 2, _Bufo vulgaris_, as examples of the arciferous type; 3, adult, 4, metamorphosing _Rana temporaria_ showing change from the arciferous into the firmisternal type; 5, _Hemisus guttatum_; 6, _Breviceps gibbosus_; 7, _Cacopus systoma_. (5, 6, 7, after Boulenger.) Cartilaginous parts are dotted; ossified parts are left white. _Cl_, Clavicle; _Co_, coracoid; _E_, epicoracoidal cartilage; _H_, humerus; _M_, metasternum; _O_, omosternum; _P_, precoracoid; _Sc_, scapula; _S.S_, supra-scapula.]