The fragment is two inches long, showing four large and obliquely set sockets in If inch. The tooth-sockets are on the outer two-thirds of the palate, and looked forward, upward, and outward The interspaces each measure 5/16ths of an inch. Each half of the palatal surface which is 5/16 of an inch wide, inclines to the other half at a right angle, being parted by a narrow groove; the diameter of the jaw is half an inch. The depth of the jaw is 5/8ths of an inch in front, and 3/4ths of an inch behind. The sides are flat and approximate below to a sharp keel. This species is one of many in the collection of W. Reed, Esq. of York, kindly placed in my hands for the elucidation of those in the Woodwardian Museum. X. Ornithocheirus Fittoni (Owen). Case. Comp. Tablet. Specimen. =J= _c_ 14 1, 2 The fragment is 1-1/2 inch long, with two large elliptical tooth-sockets on each side of the flattened palate, and one pair in front. The third socket is separated from the fourth by a considerable interspace. Between the third sockets arises the median palatal ridge, and from the inner margin of each socket a lateral ridge appears to be continued. Behind the third socket the jaw measures 11/16ths of an inch from side to side, and 10/16ths of an inch high. The sides converge and round convexly into each other. The jaws appear to have been long; It is only known by upper jaws. The type specimen shows the socket of another tooth in front of the last one figured by Prof. Owen. It is directed outward at a greater angle, and separated from the hinder one by a wall not 1/16th of an inch thick, and the teeth of this pair must have been parted from each other by a film equally thin. There is no truncation of the snout as in _O. Woodwardi_. Another specimen shows some variations. This fragment of a premaxillary bone is fractured through the third pair of tooth-sockets in front and through the seventh pair behind. It is about 2-1/8th inches long; the palate is 11/16ths of an inch wide behind the great tooth, and maintains the same width. The jaw is 11/16ths of an inch high behind, and 10/16ths high in front. The sides are gently convex, and imperceptibly unite to form the well-rounded depressed mesial ridge of the beak. From the front of the third to the back of the fifth socket measures 1-3/8ths inch. The sockets are ovate, rather smaller, and closer together than in the type of _O. Fittoni_; margins elevated. The variations from types are so many, and often so considerable, as to suggest the idea that the fossil groups called species may in the living animals have often been genera. In all the specimens the end of the palate is a little reflected upward. XI. _Ornithocheirus dentatus_ (Seeley). Case. Comp. Series. Specimen. =J= _c1_ 9 1