Soon after the publication of The Origin of Species it was realised by Huxley and others that convincing evidence of the fact of evolution might be obtained by a systematic investigation of the ancestral history and development of the Equidæ. From studying material in the British and other Museums Huxley announced at the end of the ’sixties that he believed “the Anchitherium, the Hipparion and the modern horses constitute a series in which the modifications of structure coincide with the order of chronological recurrence in the manner in which they must coincide if the modern horses really are the result of the gradual metamorphosis in the course of the Tertiary epoch of a less specialised ancestral form.” But this conclusion was soon profoundly modified. When in 1876 Huxley had the opportunity of examining the Yale and other collections of the fossil horses of America, he was satisfied that “we must look to America rather than to Europe for the original seat of the Equine series,” and “that the European Hipparion is rather a member of a collateral branch than a form in the direct line of succession.”

The embryo, as represented by the model, is bent upon itself, at the level of the cranial border of its umbilical orifice—that is, at the caudal end of the pericardial region; and, as a result of the bending, the general outline of the embryo, when viewed from the side, is hook-shaped.

The dorsal and longer limb of the hook is formed by the more caudal portion of the embryo—that is, the part which would lie caudal to the cranial margin of the umbilicus if the embryo were unbent.

The present communication is based principally on the results of a series of investigations into the form, dimensions, and characters of the skulls that comprise the unique collection which has been located in the Anatomy Department at the University of Glasgow for a number of years, and of which no account has yet been published. We owe the collection and preservation of this large and valuable series of crania—comprising over 700 specimens—to the zeal of Mr W. K. HUTTON, Lecturer in Anatomy, Queen Margaret College, University of Glasgow, to whom I am much indebted for permission to continue the work begun, but given up, by him. I am very grateful to Professor BRYCE for assistance and much encouragement during the progress of the research.

The study of human teratology has always been rendered difficult by the relative scantiness of available material; consequently it is of great importance that such cases as can be obtained should be fully utilised and recorded. It has seemed to us that in this respect the employment of X-rays is likely to prove of service, for the abnormalities of the skeletal structures can then be readily and fully studied without interfering with the integrity of the specimen or its utility in the investigation of other elements. We therefore desire to place on record the skiagraphic findings of several series of developmental anomalies in the human subject, in order that they may be available for future workers.

I am indebted to the kindness of Dr Leonard Doncaster, F.R.S., for the opportunity to examine the present collection of Terrestrial Isopoda from the Cambridge University Museum of Zoology.

The Terrestrial Isopoda of Spain have received considerable attention in the past at the hands of L. Koch,* Budde-Lund,† O. De Buen,‡ and Dollfus,§ and present many features of great interest, one of the most striking of which is perhaps the large size of the various species, particularly in the genera Porcellio, Latreille, and Armadillidium, Brandt, and to these I am now able to add the genus Cubaris, Brandt.

For two centuries and a half the ampullary canal system of Elasmobranch fishes has occupied the attention of a series of investigators, who have treated the subject from a variety of standpoints, and have amassed a considerable literature representing, in spite of repetition and some conflicting statements, a gradual advance to a fuller knowledge regarding the occurrence and the structure of the organs in question.