THE TEIAS OF GEAAFJ' EEINET, S. AFRICA. 4l7 



The correspondence between the aquatic reptile and mammal is 

 not carried out in other parts of the skeleton of the Oolitic Ichthyo- 

 saur; but in the older form under description I proceed to show 

 such in the scapula, in the chief bone of the limb articulated to the 

 complex scapular arch, and in the femur. 



Scapula. — In the ' Catalogue of South- African Fossil Eeptilia ' 

 two types of scapula are described and figured — one in a species of 

 Dicynodon *, the other in a species of Kisticephalusf. In the former 

 the marginal acromion shows an articular surface for junction with 

 . an epicoracoid ; in the other the acromion is a thinner plate and 

 does not show such distinct articular surface. The resemblance in 

 these reptilian scapulae to that bone in the Monotremes is noted $ in 

 the ' Catalogue.' 



The right scapula of Platypodosaurus (PL XVII. figs. 1 & 2) was 

 transmitted in a separate block of matrix, which had been detached 

 from that enclosing the portion of the thorax with the right 

 humerus ; it was part of the same skeleton. In clearing away the 

 matrix from such detached scapula the terminal phalanges of four 

 digits of, most probably, the fore paw of the same reptile were 

 exposed, adhering by a moderate thickness of matrix to the inner or 

 concave surface of the scapula (ib. fig. 2). This bone, as in most 

 Eeptilia, and as in the Ornitliorliynclius, is narrow in proportion to 

 its length ; a portion only of the glenoid surface for the humerus is 

 preserved at the distal end. The length, following the slight bend 

 or curve of the bone, is 10 inches ; the basal breadth is 4| inches ; 

 but some portion is here wanting from the anterior border. 



The entire bone might have shown a breadth like that of Kistice- 

 flialus, but more restricted towards the proximal end (a, b) as in Dicy- 

 nodon^. Sufficient of the fore margin is preserved to show that it de- 

 scribes, as in Dicynodon, a sigmoid curve convex along the proximal 

 half {a to 5) ; then, as the bone loses breadth, it becomes concave, this 

 curve being deepened by the production of the spine or acromion, e, 

 ^which terminates the fore border 2| inches above the distal articular 

 surface. But the fore border is as it were resumed near the inner 

 side of the acromion, completing the concave curve of that border of 

 the scapula, e' , as it advances to the coracoid articular surface, /, 

 here broken away. Hence the spine or acromion, e, may be said to 

 rise from part of the anterior border, or costa, and also from the 



ing, with Mr. Clift, the different specimens, when it struck him that there was 

 something similar to this mechanism in the sternum of the OrnitJia)''hynchus 

 2)aradoxits'' (Home, Sir Everard, in 'Phil. Trans.' 1818, p. 32, plate ii.). The 

 chief value of the papers on the " Fossil Eemains of an Animal more nearly- 

 allied to Fishes than any of the other classes of animals " (Pliil. Trans. 1814, 

 p. 576 ; 18] 6, p. 320 ; 1818, p. 32 ; and 1819, p. 216, Froteosaurus) is yielded 

 by the accurate and beautiful figures of the first discovered parts of IcMTiyo- 

 sawri contributed by WiUiam Clift, F.E.S. Cuvier subsequently pointed out the 

 correspondence of the lacertian sternal apparatus with that of Monotremes, 

 in the concluding volume (v.) of his 'Ossemens Fossiles' (4to, 1824), p. 290. 



* 0^. cit. pp. 47, 57, pis. Ixix. & kx. t Ib. p. 53, pi. Ixix. figs. 8, 9. 



:j: Ih. p. 48. § Op. cit pi. ixx. fig. 1. 



Qt. J. a. S. No. 143. 2 r 



