Among the specimens lately acquired by the British Museum from the collection of the late Mr. Beckles, of Hastings, is one to which my attention has been directed by my friend Mr. A. Smith Woodward. It bears the number R. 1926 in the Museum Register; and, like the majority of Mr. Beckles's specimens, is evidently from the Wealden. Mr. Charles Dawson, who has had so much experience in Wealden fossils, has been good enough to examine the specimen, and considers that it is almost certainly from the Isle of Wight, and not from Hastings. One glance at the specimen is sufficient to show that it is the central part of a Dinosaurian ilium, with portions of the sacral ribs still attached to its inner surface. It belongs to the right side, as proved by the position of the ischial tuberosity; and while both extremities of the ilium are wanting, the acetabular region is fairly well preserved. The pre-acetabular portion of the ilium forms a roof-like expansion; while the post-acetabular process is compressed and comparatively thin. The upper border of the ilium is straight. The broken portions of the sacral ribs (five in number) are triangular in section, and have deep indentations between them; so that they form buttress-like structures of great strength. The whole contour of the ilium and sacral ribs is quite unlike that obtaining in Iguanodon and its allies. It appears most likely that the pre-acetabular portion of the ilium when entire was greatly expanded laterally, as is