Four specimens which show articular ends such as the ulna should have, are mounted together. They are compressed bones with the section of the fracture elongately oval; and the shaft widens from the fracture to the articulation without increasing in thickness. The outer surface is gently convex, becoming concave mesially near the articulation; the inner surface has the same characters, only the concavity at the extreme distal end reaches from side to side of the bone. The two short sides both look outward as well as laterally; one of them flattened so as to thicken the bone, is concave in vertical outline owing to the extreme distal end turning suddenly outward; the other side a little convex, compresses the bone and inflects its inner margin. The longest specimen measures 1-5/8 inch; 5/8 inch wide at the fracture, and 1-1/8 inch wide at the distal end. The greatest thickness at the distal end is half an inch, the thickness of the fractured shaft is 5/8 of an inch. The articular surface appears to have an elongated sub-reniform shape, the part at the compressed side of the bone being narrower than the broad ovate part on the thick side of the bone, to the lateral limit of which it extends, while the narrow part does not extend laterally nearly so far as the inflected border, which appears to give attachment to powerful muscles. There is also a strong muscular attachment at the corresponding diagonal corner of the bone where the outer surface on its right meets the side of the bone in an elevated ridge. In its long diameter the articulation is a little convex; transversely it is very convex in the ovate part, but more flattened in its narrower continuation. Where widest it measures about 4/10ths of an inch. Nos. 5 and 6 on another tablet appear to be distal ends of ulna of another kind of Pterodactyle. They are less compressed, more quadrate in section, and have the sides more nearly parallel The flattened side similarly has a concave border, but instead of having its distal termination developed laterally, has it thickened behind. The opposite side of the bone which in the other specimens was compressed is here thick and well rounded, and not at all inflected. There is an absence of the concavity noticed on the outer surface of the bone in the compressed specimens. The articular surface is much flatter, and a little concave in length instead of being convex; as in the other examples it looks downward. The largest fragment. No. 5, measures 1-3/8 inch long; it is 6/8 inch wide at the fracture, and 4/8 inch thick. The sub-quadrate distal end is more than an inch long, more than 4/8ths inch thick on the thick side, and nearly 4/8ths inch thick on the compressed side. II. Distal End of Radius.