74 SHOULDER-GIRDLE AND BREAST-BONE. 



the mid-line, and backwards towards the Sternum. The posterior margin of this coracoid 

 fenestra (cr. f.) is formed by the coracoid (cr.), and the anterior and inner by the broad 

 epicoracoid cartilage (e. cr.) ; this latter margin is so accurately semi-oval that it seems as if it 

 were artificially cut ; it does not reach the mid-line of the body by three and a half lines. The 

 whole extent of the basal cartilage is two inches eight lines, and its widening sides are to some 

 extent converted into perfect bone by the prae-coracoid (p. cr.) in front, and the coracoid (cr.) 

 behind. The former of these is only formed at the anterior edge, and clamps it on both sides ; 

 is pedate where it helps to form the glenoid cavity, and then becomes a narrow, slightly curved 

 bone, which ends at the same distance from the lower edge as the " fenestra." The coracoid 

 (cr.) has a small head, a rather more constricted neck, and then at the middle has begun to 

 widen ; so that whilst it is less than two lines wide above, it is nearly an inch across below, and 

 reaches the mid-line within two lines. The extensive, partially calcified prse-epicoracoid cartilage 

 runs behind the prse-coracoid outer plate, nearly to the glenoid cavity ; runs in front of it against 

 the mid-line, forming an "omosternal" lobe (o. st.), five lines long by four broad; mounts upon 

 the front margin of the coracoid for three lines in extent, and runs round its base, forming a 

 plate equal in size to the main bone (cr.), behind which it sends a broad ascending process. 

 This extension of the epicoracoid behind the coracoid as a hook or spur is repeated again and 

 again in the Oviparous Vertebrata, and I shall show how very marked a character it is in a large 

 number of Birds ; that which is most noteworthy in Pipa is the great relative size of this 

 hook. 



What is most remarkable of all in the Shoulder-girdle of this strange Toad, is the per- 

 fectly straight " harmony -suture," formed by the meeting of the right and left prae-epicoracoids 

 (for in most of the Anoura, even when very small, they overlap) ; and the long, slightly sinuous 

 "harmony-suture" of the epicoracoids with the Sternum (st.) on each side. The former suture 

 is nearly two inches in extent ; the two latter are each more than one inch. What there is of 

 the submesial cartilage in Dactylethra is straight also (Plate VI, fig. 10), and in Ceratophrys 

 (Plate VI, fig. 2) this line is almost straight; but for extent and perfection they bear no com- 

 parison with Pipa. About a line breadth of margin is left soft along the front of the " omosternal" 

 lobe, and along the hinder margin of the ascending posterior spur of the epicoracoid (e. cr.) ; all 

 the rest of the cartilage is composed of two plates of granular bone, with a pith of unchanged 

 cartilage within. 



The Sternum of Pipa (Plate VI, fig. 1, st.) challenges attention equally with the rest of 

 the thorax-plates ; and this, not only on account of its huge horizontal expansion, but because it 

 is arrested at that same morphological condition which we find temporarily in the Common Frog 

 at its first exit from the water when it has been fairly curtailed. The long sutures of the 

 Sternum with the epicoracoids have been described ; they form with each other rather more than 

 a right angle. The free edges of the Sternum are of equal length with the others, but they are 

 concave at the middle, and swell at both ends; whilst the xiphoid extremity , x not at all produced, 

 is rounded exactly like the " omosternal " rudiments ; this rounding of the free part of the 

 Sternum spoils the otherwise very regular lozenge-shape. Measured fore-and-aft, and from angle 

 to angle, the Sternum is more than one and a half inch ; the latter measurement being slightly 

 the longest. In the condition of its ossification it answers exactly to the pra-epicoracoid, and 

 the free margin has the same amount of soft cartilage. 



The Pipa seems to me to be one of those beautiful instances of " shifting of hands" which we 



