No. 1 shows a well-marked pit for the ligamentum teres at the back part of the ball. At the proximal end of the shaft below the neck is a large pit for the obturator muscle, and at the outer front angle a great trochanter. Proximally the bone can only be compared with the mammalian Carnivora, Quadrumana and Man; distally it is avian and mammalian. In one genus exemplified by specimens 5-10 the obturator pit is not developed. Sometimes the shaft is curved a little convexly, outward and forward. TIBIA. Pl. 8. Case. Comp. Tablet. Specimen. =J= _b_ 12 1-11 Eleven specimens are mounted to illustrate the tibia, of which 1 to 9 are regarded as proximal ends; and 10, 11 with less confidence are regarded as distal ends from which the distal epiphysis has come away. It is to be anticipated that the distal end of the tibia in Pterodactyle will when found approximate to the distal end of the tibia in the bird. The bone is at the proximal end straight and sub-cylindrical, slowly enlarging proximally; convex behind, except for an elevated boss some little way below the proximal articulation for the attachment of powerful muscles. In front the shaft is a little flattened proximally, with a mesial groove dividing two prominences which are apparently homologous with the ridges below the patella in birds. The proximal articular surface truncates the shaft at right angles except at what is regarded as the outer front aspect, where it rises into a small patelloid prominence. It shows the impressions of two condyles, which correspond in form with the distal end of the Femur. Nos. 3 and 6 are regarded as left tibia; Nos. 4, 5, 7, 8, 9 as examples of right tibia. No specimen likely to be a fibula has been found. In Dimorphodon and in German Genera the fibula is Avian in form. The Crocodile offers some approximation to the Pterodactyle shape in the proximal end of the Tibia, but the Pterodactyle has Avian characters in addition. Its straightness and length, ridges on the front and patelloid prominence, are Avian. TARSUS OR TARSO-METATARSUS. Pl. 8. Case. Comp. Tablet. Specimen. =J= _b_ 13 1 This fragment, which may be the distal end of the bone corresponding to that called in birds the tarsus or tarso-metatarsus, is badly preserved. Yet so close is its resemblance in form, structure, and apposition of the constituent bones to what obtains among birds, that it may probably be identified as the tarsus; while the peculiar characteristics of Pterodactyle bones which it shows, demonstrate that it is not from a bird, but from an Ornithosaurian skeleton.