70 SHOULDER-GIRDLE AND BREAST-BONE. 



massive and broad bone ; whilst the prse-coracoid (p. cr.) is a very small phalangoid bar. Here 

 we have the normal proportions of the ischium scaApubis of the Mammal. The coracoid fenestra 

 (cr. f.) the counterpart of the obturator foramen of the Mammalian pelvis, is very small, oval, and 

 has its narrow end pointing forwards ; the reverse of what obtains in 8. gibbosum. The Sternum 

 (st.) is twice as large as in the former species, more normal in form, and ossified as in the other 

 kind. 



A 5. Typical in all things save in the absence of the " Omo-sternum ;" the supra-scapula 

 being large ; the scapula cleft below ; and the prse-coracoid separated from the coracoid by a 

 large " fenestra." 



Example 1. Ceratophrys dorsata, Neuwied. 



Plate VI, figs. 2 and 3 show the Shoulder-girdle of an adult male of this species (from 

 the Brazils), fig. 2, being an upper, and fig. 3 a side view ; they are both of the natural size. 

 Here we see the large oblong supra-scapula (s. sc.), which is somewhat pinched at its middle, 

 having its imperfect outer bony plate covering rather more than the front half ; but notched 

 below and arrested above, and having underlying it an independent endosteal growth, which 

 still leaves much of the upper and hinder part unossified altogether. The scapula (fig. 3, sc.) is 

 a long, flat, boot-shaped bone, of considerable breadth above, and then having an ankle-like 

 narrowing before it gives off its prse-scapular bar (p. sc.) The bony, outer plate, which only 

 crept from the front margin to a certain extent on both sides of the supra-scapula, has thoroughly 

 ensheathed the scapula ; so it does in the coracoid (cr.) ; but not in the prse-coracoid (p. cr.). 

 This latter bone is crescentic in shape, broad above, pointed below, and is clamped on to the 

 partially ossified cartilage like the back of a meat-saw. The coracoid, separated from the prte- 

 coracoid by a large tear-shaped fenestra (cr. f.), is a stout ray of the typical form, that form which 

 also we shall see to be the rule in the Bird-Class. The epicoracoid belts (e. cr.) are flattened, 

 but are undiminished in breadth, are endosteally ossified, and do not overlap each other. The 

 back of the glenoid cup (gl.) is seen to form a notable bulb on the inside, whilst on the outside 

 (fig. 3) we see that it owes most of its wall to the coracoid, and least to the prse-coracoid. The 

 Sternum (fig. 2, st., x. st.) is relatively the largest in the group, and has the prse-mesosternal 

 region ossified by endostosis, all but the low triangular apex ; the xiphisternal portion (x. st.) is 

 unossified, and shows its primordially symmetrical character by being divided into two large 

 neatly rounded lobes. 



Example 2. Docidophryne giyantea^ Fitzinger. 



Plate VI, fig. 4, shows the Shoulder-plates of this huge Batrachian, of the natural size, and 

 as seen from above. Professor Hyrtl's preparation is marked as an adult female from Mexico. 

 The supra-scapula (s. sc.) is very large, and somewhat oblong, but with a concave anterior and a 

 convex posterior margin ; the upper edge is gently rounded ; ossification has advanced much 

 further than in the last species, but is of the same character. The scapula (sc.) is a robust bone, 

 considerably constricted in the middle, and having a very definite basal fenestra (sc. f.) : its suture 

 with the prse-coracoid is very extensive. The prse-coracoid (p. cr.) is very broad above, and then 



