THE late Rev. W. D. Fox, of Brighstone (Isle of Wight), discovered in the Wealden Beds of Brook in that island many associated ornithosaurian bones. These were acquired by the Trustees of the British Museum in 1882, when they purchased his important collection. They are numbered R/176, and classified by Mr. R. Lydekker under Ornithocheirus nobilis (Owen) as 'not improbably belonging to this species.' In 1888 the hinder portion of the skull was shown by Mr. Lykedder to Mr. E. T. Newton, at the time when the latter was preparing his paper on Scaphognathus purdoni; and Dr. Henry Woodward permitted it to be bisected longitudinally, so that Mr. Newton was enabled to describe the form of the brain. No other reference appears to have been made to the fossil until 1901, when the late Prof. H. G. Seeley referred to it in his 'Dragons of the Air' (pp. 173–74), under the name of Ornithodesmus latidens, and thus it became the type of that genus. Judging from particulars there given, one would surmise that a much greater portion of the skeleton once existed. At the present time the hinder part of the cranium is the only moiety of the skull to be found; but Dr. A Smith Woodward informs me that he has heard a tradition that Fox had originally the jaws of this specimen, and that they were lost before the collection came into the possession of the British Museum. I purpose giving details of the bones comprised in B.M.