A fragment of premaxillary bone two inches long, fractured behind the socket for the seventh tooth. It most nearly resembles _O. Sedgwicki_ and _O. Cuvieri_. Behind the second tooth the palate is 1/2 an inch wide; behind the sixth socket it is 5/8ths of an inch wide; the distance between these points is nearly 1-1/2 inch. The palate is flattened, with a sharp slight mesial keel and a wide concave channel on each side which dies away in front. The first pair of teeth are in front of the snout, rather small, and look forward. In this specimen the large third tooth is not developed on the left side. The second and third sockets are large and close together; the succeeding teeth are parted from each other by interspaces equal to their own diameter. They are gibbously elliptical. The sides of the jaw are gently convex from above downward; they round into each other to form a narrow rostral keel. Behind the second socket the jaw is 1/2 an inch high; behind the sixth it is nearly 7/8ths of an inch high. The grooved and relatively wider palate, and the relatively smaller teeth, abundantly distinguish this species from _O. Sedgwicki_ (Owen). The smaller, more circular teeth, placed closer together, distinguish it from _O. Cuvieri_ (Bowerbank). XII. Ornithocheirus scaphorynchus (Seeley). Case. Comp. Tablet. =J= _c_ 22 This fragment of premaxillary bone is 1-1/2 inch long. The palate is 1/2 an inch wide behind, and the jaw is rather more than 1/2 an inch high; behind the second tooth it is nearly 5/8ths of an inch high. The sides converge superiorly to form a well-rounded keel. The palate is flattened, with a slightly elevated blunt median keel. There appears to be a pair of small teeth in front of the snout as usual, and six on the palate, with an indication of another at the posterior fracture. The teeth are of moderate size and almost circular. In the form of the bone it is readily distinguished from all the species enumerated. XIII. Ornithocheirus platystomus (Seeley). Case. Comp. Series. Specimen. =J= _c6_ 32 1 An ill-preserved fragment fractured in front and behind, yet indicating a distinct species. The palate is flat, with the faintest median ridge, and the sides are flat and round into a narrow rostral keel, which in front approximates rapidly towards the palate. The first pair of sockets are missing; what appears to be the second pair are about 1/8th of an inch long, separated from the pair behind by an interspace of 1/4th of an inch. These are ovate and less than 1/4th of an inch long, and separated from the next pair by an interspace of not less than 1/4th of an inch. The height of the jaw over the first pair of sockets preserved is 9/16ths of an inch; over the second pair it is 14/16ths of an inch; the space between these points is 9/16ths of an inch. Behind the second pair of teeth the palate is nearly 5/8ths of an inch wide.