444 BRITISH FOSSIL REPTILES. 



The rich repository of remains of gigantic Pterosauria in the Upper Green- 

 sands of Cambridgeshire have added valuable evidence on these important points, 

 and demonstrate a nearer approach to the keeled character of the breast-bone of 

 flying birds than the specimens of the smaller species described in the under- 

 cited works appear to demonstrate. By the kindness of Professor Sedgwick, I 

 am enabled to compare the specimens of portions of the sternum acquired by the 

 Woodwardian Museum with that which has recently been purchased by the 

 British Museum. The best of these specimens consist of little more than the 

 thicker and stronger, contracted fore part of the breast-bone (PI. 12, figs. 7, 8, 

 and 9), broken away from the thin, expanded, fragile plate (/*), of which it princi- 

 pally consists, and of which remains or impressions have been preserved in a few 

 slabs of fine-grained stone of the Oolitic series, such as the lithographic slate ; 

 that of Pterodacfi/les suevicus* showing the posterior border of the symme- 

 trical plate to be convex and entire, not notched or perforated, as in many birds. 

 The fore part of the sternum of the gigantic Pterodactyle from the Cambridge 

 Green-sand includes the major part of the anterior process, and also the pair of 

 articular facets for the coracoids. The keel-like process in the specimen (PI. 

 12, figs. 7, 8, 9, i, e, f) is continued forward from that articular region (rf, c), for 

 an extent equal to the depth of the bone at the same part ; but the process is not 

 entire. Its base is gently convex at the sides, from the middle and thickest part 

 of which it gradually narrows to a ridge, at about a line or less in thickness at 

 both the upper and under margins ; the extreme fore part being broken away, 

 prevents the determination of the precise extent or contour of that end, but the 

 convergence of the preserved parts of the upper and under margins indicate a 

 convexly rounded termination (fig. 7, e). There is a gentle depression on each side 

 of the beginning of the upper part of the ridge, which ridge is continued from a 

 thickening or tubercle (figs. 7, 8, 6), bounding anteriorly a small, deep, transversely 

 oval depression (d) between the two articular surfaces for the coracoids (c). This 

 tubercle answers to what I have termed the " manubrial process " in the sternum 

 of birds.t and the above pre-coracoid part of the sternum answers to that process, 

 confluent below, as in Jjjfeuodj/fes, with the produced " keel." This, however, in 

 Pterodadyles, quickly loses depth as it extends backwards along the mid-line of 

 the under part of the sternum, some way behind the articular region, and has 

 not quite subsided at the fore part of the expanded body of the breast-bone (fig. 

 9, /), from which the rest of the shield-like plate has been broken away. The 

 sides of the post-coracoid part of the keel are gently concave ; the lower border of 

 the keel is first convex, then concave to near its posterior termination, both in a 

 very feeble degree (fig. 7, e, f). Each of the articular surfaces for the coracoid 



* Quenstedt, ' Ueber Pterodactylus suevicus, im Lithographischen Scluefer Wurtembergs,' 4to, 1855, 

 t Art. " Aves," ' Cyclopaedia of Anatomy and Physiology,' vol. i, 1836, p. 282, fig. 129. 



