ANNIVERSARY ADDRESS OF THE PRESIDENT. lxxix 



" The author's reserve, in treating upon a subject so vast and 

 difficult, cannot but be approved, although no one can fail to perceive 

 that the memoir of M. D'Orbigny has enriched science with a great 

 number of new facts and with many ingenious speculations. New 

 observations may hereafter lead to a modification of some of his 

 theoretical views ; but the merit will always be his of having con- 

 sidered a vast subject from a point of observation so elevated as must 

 necessarily cause it to command attention, and lead the way to still 

 further progress. "We therefore propose to the Academy that it should 

 express to the author the high satisfaction it has experienced in con- 

 templating the indisputable advancement which has been made 

 towards a knowledge of the geology of South America, by his cou- 

 rageous and persevering researches : " — let me also add, towards a 

 knowledge of the geology of all parts of the earth ; for his great works 

 on the Palaeontology of France deserve such a commendation. 



Having now, I trust, faithfully performed my duty towards those 

 illustrious members whom we have lost, and who during their lives 

 were active either in promoting the progress of our own science or 

 in advancing the general knowledge of mankind, I will turn to a 

 work not so embittered by painful recollections, and proceed to esti- 

 mate the labours of the past year. 



The present Session has been characterized by the excellence and 

 importance of its Palseontological papers : the first was contributed 

 by Professor Owen, who exhibited and described an almost entire 

 lower jaw, with the permanent dental series, wanting only four middle 

 incisors, of an Anoplotherioid quadruped, from the collection of the 

 Marchione s of Hastings, and now forming part of the Palseonto- 

 logical collection in the British Museum. 



From the equality of height of the crowns of the teeth, and their 

 general character, Professor Owen considered the animal as belong- 

 ing to that group of the Anoplotherioid family which includes the 

 genera Dichobune and Xijphodon of Cuvier, the animal being of the 

 size of Cuvier's X. gracilis. The author then described in detail the 

 dentition of the specimen, and pointed out its difference from that 

 of Dichodon, and of Xiphodon, as also its agreement with that of 

 Dichobune, with which genus therefore he associated it provisionally, 

 in the absence of a knowledge of the molars of the upper jaw ; and, 

 after a comparison with the Dichobune leporina of Cuvier, he formed 

 it into a distinct species, Dichobune ovina, from the size of the animal. 

 The Dichobune cervina of his ' British Fossil Mammals' he transferred, 

 on the suggestion of M. Gervais, to the genus Dichodon. 



Professor Owen then compared the genus Xiphodon with the genus 

 Dichobune. The first had originally formed part of the genus Ano- 

 plotherium ; but the species A. medium, Cuvier, afterwards called by 

 him A. gracile, was subsequently separated by Cuvier, and made the 

 type of a new genus Xiphodon, as X. gracilis, to which Gervais (in 

 ' Paleontographie Francaise') afterwards added the Xiphodon Gey- 

 lensis, and described the dental series of both jaws of the typical species 



