Sept. 27, r883] NATURE srs on the subject, and am anxious to state one or two matters which I learned from him concerning questions raised in my review. Prof. Marsh has visited Brussels since I was there, and since M. Dolle's memoirs referred to by me were in print, and has examined the Iguanodon skeletons with M. Dollo, this being the second occasion on which he has seen the collection. After having examined the specimens now available he is of opinion that the question whether the bones

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... ered by M. Dollo to be sternal are in reality such, or clavicles, is still an open one. The form of the bones, which are u ndoubtedly identical with those in the British Museum specimen determined by Prof. Marsh to be clavicles, is exactly that of clavicles and unlike that of any known sternal bones. There can be no doubt that they belong to the pectoral arch, but the position in which they have been found in two Bernissart specimens points to their belonging ra ther behind than in front of the coracoids. It is, however, Prof. Marsh believes, jnst possible that they may have fallen forward into the position in which they there occur, and he awaits the results to be attained from their examination in the other Berni-sart specimens before making up his mind. In the closely-allied H ypsilophodon the sternum is a single broadkeeled plate. In the case of the British Museum specimen one of the bones is attached to the scapula. At all events, he points out that, should these bones really prove to be sternal, it does not follow that Iguanodon had no clavicles a t all, for there is a process on the scapula indicating the presence of a clavicle, and such a bone, possibly very small and rudimentary, may yet be found to exist. The statement of Prof. Marsh that the post-pubis in Iguanodon j , long and slender, and incomplete, is correct; the conclusion that it was not w arose from a misundet·standing of the exact meaning of the term incomplete, as used. It denotes that in J guanodon the bone does not extend, as it does in some Dinosauria (Hypsilophodon), Lack wards as far as the ischia, or farther, as in some birds, and this, as will be seen by r eference to the figure is the case in Iguanodon, in which the post-pubis does not extend much further back than just beyond the ischial tuberosity. The fact is proved clearly by British specimms as well as by those of Rernissart. Prof. Marsh has observed that in two or three of the Bernissart skulls sutures are distinctly to be seen. H. N. MOSELEY