president's address. 21 



nasal area, which rested on this elongated lower jaw, by the shortening 

 (in the course of natural selection and modification by descent) of 

 this long lower jaw, to the present small dimensions of the elephant's 

 lower jaw, and the consequent down-dropping of the unshortened upper 

 jaw and lips, which thus become the proboscis. Dr. Andrews has de- 

 scribed from Egypt and placed in the Museum in London specimens of two 

 new genera — one Palseomastodon, in which there is a long, powerful jaw, 

 an elongated face, and an increased number of molar teeth ; the second, 

 Meritherium, an animal with a hippopotamus-like head, comparatively 

 minute tusks, and a well-developed complement of incisor, canine, and 

 molar teeth, like a typical ungulate mammal. Undoubtedly we have in 

 these two forms the indications of the steps by which the elephants have 

 been evolved from ordinary-looking pig-like creatures of moderate size, 

 devoid of trunk or tusks. Other remains belonging to this great mid- African 

 Eocene fauna indicate that not only the Elephants but the Sirenia took 

 their origin in this area. Amongst them are also gigantic forms of Hyrax, 

 like the little Syrian coney and many other new mammals and reptiles. 



Another great area of exploration and source of new things has 

 been the southern part of Argentina and Patagonia, where Ameghino, 

 Moreno, and Scott of Princeton have brought to light a wonderful series 

 of extinct ant-eaters, armadilloes, huge sloths, and strange ungulates, 

 reaching back into early Tertiary times. But most remarkable has been 

 the discovery in this area of remains which indicate a former con- 

 nection with the Australian land surface. This connection is suggested 

 by the discovery in the Santa Cruz strata, considered to be of early 

 Tertiary date, of remains of a huge horned tortoise which is generically 

 identical with one found fossil in the Australian area of later date, and 

 known as Miolania. In the same wonderful area we have the 

 discovery in a cave of the fresh bones, hairy skin, and dung of 

 animals supposed to be extinct, viz., the giant sloth, Mylodon, and the . 

 peculiar horse, Onohippidium. These remains seem to belong to survivors 

 from the last submergence of this strangely mobile land-surface, and it is 

 not improbable that some individuals of this ' extinct ' fauna are still 

 living in Patagonia. The region is still unexplored and those who set out 

 to examine it have, by some strange fatality, hitherto failed to carry out 

 the professed purpose of their expeditions. 



I cannot quit this immense field of gathered fact and growing 

 generalisation without alluding to the study of animal embryology and 

 the germ-layer theory, which has to some extent been superseded by the 

 study of embryonic cell-lineage, so well pursued by some American 

 microscopists. The great generalisation of the study of the germ-layers 

 and their formation seems to be now firmly established — namely, that the 

 earliest multicellular animals were possessed of one structural cavity, the 

 enteron, surrounded by a double layer of " cells, the ectoderm and 

 endoderm. These Enterocoela or Coelentera gave rise to forms having a 

 second great bod jr- cavity, the coelom, which originated pot as a split 



