Notices of Memoirs — Dr. Andrews — Evolution of Prohoscidea. 225 



it is, or used to be, transported for long distances. It is somewhat 

 similar to the Eedscar Grit of Wolfry Crags, but is quite unlike the 

 general character of this bed. 



It is noteworthy that I found near the base of the Eedscar Grit 

 in Gateup, bands of calcareous sandstone. Similar bands, "Bs I am 

 informed by Mr. J. G. Goodchild, generally occur under the rock 

 which in Wensleydale was identified on purely stratigraphical 

 grounds with the Eedscar Grit. 



This grit is the 'middle grit' of the late Professor Phillips 

 mentioned on p. 65 of his " Geology of the Mountain Limestone 

 District," and he is quite correct in saying that it corresponds in 

 position with the top grit of Penhill. 



O^OTICES OIF DVCEUVCOIE-S, IBTO. 



On the Evolution of the Proboscidea. By C W. Andrews, 

 D.Sc, F.G.S., F.Z.S., of the Geological Department, British 

 Museum (Natural History).^ 



UNTIL the author's recent discoveries of primitive Proboscidea 

 in the Middle and Upper Eocene formations of the Fayum, 

 Egypt, the oldest known members of this mammalian order were 

 Dinotherium Cuvieri and Tetrabelodon angustidens, from the base 

 of the Miocene in France. The new Egyptian fossils not only 

 reveal for the first time the early history of the order, but also 

 provide more satisfactory material for the discussion of its evolution 

 than has hitherto been available. 



The most important changes in the Proboscidea occur in the skull, 

 mandible, and dentition. 



Owing to the increase in the size of the tusks and to the presence 

 of the proboscis, the facial region of the skull becomes shortened, 

 and at the same time the premaxillae become wider. The presence 

 of the proboscis also accounts for the position of the external nares. 

 The demand for a greater surface of attachment for the muscles 

 supporting a skull rendered heavy by the tusks and trunk, is met 

 by the great development of the diploe in certain of the cranial 

 bones, resulting in the enormous expansion of the forwardly sloping 

 occipital surface. The maxillse become greatly enlarged con- 

 comitantly with the increase in the size and degree of hypselodonty 

 of the molars. At the same time the zygomatic arch becomes 

 weaker and the jugal takes a smaller share in its composition. 



The mandible is at first short and stout, with a massive symphysis. 

 Afterwards it becomes more and more elongated as the stature of 

 the animals increases ; and this elongation is for the most part 

 effected by the lengthening of the symphysial region, though the 

 backward rotation of the ascending ramus tends to the same end- 

 The prolongation of the mandible beyond the premaxillas must 

 have been covered by a proboscis-like structure composed of the 

 upper lip and nose, probably more or less prehensile at its extremity. 



' Abstract of a paper read before the Royal Society of London, March 26th, 1903 ; 

 communicated by Professor E. Eay Lankester, F.R.S. 



DECADE IV. — VOL. X. — ^NO. V. 15 



