■.G.16 .: PROF. n. A. wAiit ON 'jMrK 



seem to link tlie Zeuglorlontidas more closely with Insectivore 

 antecedents. In the meantime, the intimacy of tiie lelationsliip 

 between Zenglodontidai and Cetacea has been reallirmed by 

 numerous observers, including amongst many. others Abel (1905- 

 •1913) and Winge (1919,' 1921). 



Previous investigation of the group has naturally centi-ed 

 .around the osteological remains, and has shown (Andrews, 1907) 

 that they probably arose " on the northern shores of the 

 JJthiopiah land in the early part of the Eocene period," and that 

 " by the end of the Middle Eocene the true Zeuglodonts had 

 .come into existence, and had, spread rapidly over the earth, their 

 remains being found in the upper part of the Eocene of Americn, 

 England, and New Zealand." 



Since the appearance- of Professor G. Elliot Smith's important 

 contribution to the study of the form of the endocranial cast 

 (1903) no new feature of the cerebral anatomy of these foims has 

 been recognised, so far as I have discovered, although Stromer 

 (1908) has figured v/hat is apparently a unique natural endo- 

 cranial cast in a form which he styles Zeuylodpn osiris. 



Shortly after the publication of Professor Elliot Smith's article, 

 Mr. H. J. L. Beadnell gave him an almost perfect natural endo- 

 cranial, cast of a Zeuglodont collected in the Egyptian Eayum at 

 the locality known as the Gar-el-Gehannem. Professor Elliot 

 Smith kindly placed it at my disposal some time ago. I was assisted 

 in the ''development" of this natural cast by Professor D. M. S. 

 Watson, who carefully removed most of the adherent bone and 

 matrix, giving the I'esult which has been accurately reproduced 

 by Miss Davison in text-figs. 1, 2, and 3. This specimen has 

 since been. given to the British Museum by Professor G. Elliot 

 Smith and is distinguished by the collection number M. 1212li. 

 The majority of the rematining figures have been drawn by 

 Mr. Poulton, artist to the Anatomical Institute of University 

 College, London. 



Owing to the courtesy of the British Museum officials, of 

 Dr. A. Smith Woodward, and especially of Dr. 0. W. Andrews, 

 who has assisted me at every turn in this work, I have been able 

 to draw upon the paleontological resources of tliat institution. 

 The Zeuglodont material there has been examined and extremely 

 satisfactory casts made of the brain-cases, through the skilful 

 work of Mr. L. E. Parsons. 



The conclusion of this research would have been impossible 

 apart from the courtesies that have been extended to me not only 

 • by the above-mentioned persons, but also by Sir Arthur Keith 

 and Mr. Burne of the Royal College of Surgeons. To one and all 

 .1 tender my grateful thanks. 



2. Material. 



One of the most important results that has emerged from the 

 research is the definiteness with which Ave can now determine 



