68 SHOULDER-GIRDLE AND BREAST-BONE. 



its surface covered with the outer bone, and nearly all the rest hardened, superficially, by endo- 

 stosis; a narrow band of soft cartilage connects it with the scapula (sc.), which is hourglass- 

 shaped in outline. The concave anterior outline of the scapula is interrupted by a small spur, 

 and the inner face has, along its middle, a strong smooth keel, relatively larger than the outer 

 scapular spine of the Echidna. Below this spine the scapula bifurcates, and the hinder, short 

 division forms half the glenoid cavity (gl.) ; whilst the longer spur runs forwards, meeting the 

 head of the coracoid : the whole scapula looks very much like a high-heeled boot with the toe 

 part forwards. This is the normal form of the scapula in the Anoura ; but the coracoid (cr.) 

 of Hyladactylus is not normal, for it is merely one narrow-waisted, broad-ended bar, flattened, 

 and yet tolerably thick, with the broadest end below ; there is but little soft epicoracoid below, 

 for the outer bone is well developed in this as in many other Frogs. This form of coracoid will 

 reappear constantly in the Bird Class with a few modifications. The Sternum (st.) in this species 

 is very large, and not unlike the blade of a cheese-knife ; the prae-mesosternal part is broad, but 

 the xiphisternal end (x. st.) is more than semicircular, and has produced angles, looking forwards ; 

 the whole cartilage has but one two-layered, imperfectly developed ossification (endostosis), the 

 margin all round the plate being soft. 



A 3. Supra-scapula inordinately large ; scapula minute and undivided ; prse-coracoid 

 nearly as large as the coracoid, and separated from it by interruption of the epicoracoid 

 band. 



Example. Dactylethra capensis, Cuv. 



In Plate VI, figs. 10 12, the Shoulder-girdle and Sternum of this extraordinary Frog are 

 shown, magnified two diameters. The specimen was prepared from an adult female individual. 

 In this form the supra-scapulse (s. sc.) are so large and thin, that they look like the epicoracoids of 

 the Salamander turned upside down. In outline they are bagpipe-shaped, and the ectosteal bone, 

 perfect in the narrow oblique lower part, only covers two fifths of the cartilage above. This 

 outer bone spreads above into two unequal leaves with toothed edges, the small leaf being the 

 one in front, and having, underlying it partly at its upper margin, an independent endosteal 

 patch, which is kidney-shaped. The free, thin, soft edges are quite as capable of overlapping 

 each other as the epicoracoids of the Salamandrines, and make a very ridiculous figure as 

 the capitular and tubercular parts of "occipital pleurapophyses." The extreme variability 

 in the relative size of morphological regions and elements is well shown in Dactylethra; 

 for, combined with the largest supra-scapula, we find the minutest scapula (figs. 10 and 

 11, sc.). 



This bone is a short, thick wedge, concave within, having an upper and a lower thick lip, 

 externally, with a fossa between ; and there is no trace of morphological cleaving ; it is well ossified, 

 and is separated by a narrow band of cartilage from the supra-scapula above, the prse-coracoid 

 (p. cr.) in front, and the coracoid (cr.) below. These three bones are united in the base of a 

 most elegant acetabuliform glenoid cavity, by a three-rayed suture, exactly like a Mamma- 

 lian "acetabulum," and having the edge of the cup chipped below, for the ligament, in precisely 

 the same manner. The prae-coracoid (p. cr.) joins the supra-scapula in front of the scapula, a 

 most rare connection, and showing that morphological " law" is neither blind nor bound, and 



