The fragment is 2-7/8ths inches long, with the elliptical teeth opposite to each other, 6 on a side on the palate, and one pair in front. The first three teeth are large; behind these the teeth are about half the size. The palate is gently convex, with a faint median ridge, and measures from side to side over the fourth and subsequent sockets 13/16ths of an inch. The height of the jaw at the fourth socket 1-1/4 inch. The sides converge to an acute rounded rostral keel. The jaws appear to have been long. The anterior termination is vascular. The rostral keel figured by Owen Pl. I, fig. 1 _d_, in the 1st Supt. _Cret. Reptiles_, is not square as represented there, but rounded; the sides converge more acutely, and at the ridge the keel is not half so wide as the figure makes it. The enormous size of the third tooth-socket is partly due to the cracked bone having absorbed more phosphate of lime than it could hold, and extended the cracks to fissures. The type specimen shows that there was another pair of sockets in front of, but quite close to, those which appear to terminate the lower jaw. II. Ornithocheirus Cuvieri (Bowerbank). Case. Comp. Tablet. Specimen. =J= _c_ 15 1-3 A portion of a premaxillary bone fractured at both ends, and two inches long, corresponds with Dr Bowerbank's fossil figured Pl. XXVII. fig. 1, 3, 4, in the Palæontographical volume for 1851. The palate is just as wide; the median ridge, the same; the teeth the same in shape and as far apart. The jaw is of the same depth, but does not deepen so rapidly behind. The only other difference is that the sockets of the teeth are less prominent on the sides, and appear to look more directly down. The ridge in which the converging sides meet is well rounded in a dentary bone which may have pertained to this species. In the space of two inches and a quarter are 5 teeth, the posterior four extending over two inches, the other pair being in front. The palatal surface is 3/4 of an inch broad behind the third tooth, and rather more than 5/8 of an inch broad behind the fourth tooth. The length of the 4th or of the 5th sockets is two-thirds that of the second or third. In front of the 5th tooth, the jaw is an inch deep, and it tapers in a curve to the anterior end. The teeth behind the third have interspaces greater than the length of the sockets; that between the 4th and 5th being 3/8 of an inch, while the socket only measures a quarter of an inch long. Behind the 2nd socket commences the palatal groove, broad in fronts but narrowing behind; and its sides instead of diverging as in the type, are concave so as to form a channel like a straightened _Siliquaria_ shell. The halves of the palate bevel off so as to make a right angle with each other, and greater angles with the flat sides. III. Ornithocheirus machærorhynchus (Seeley). Case. Comp. Tablet. Specimen. =J= _c6_ 35 1