136 PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



Dino'fherium, in which the lower canines are laterally compressed, whereas 

 in all the longirostral bunomastodonts the lower canines are vertically com- 

 pressed. 



All these hunomastodontina' are very readily distinguished from the typical 

 Mastodontinw, a line which is relatively conservative in its evolution, since the 

 "intermediate" molars remain trilophodont and the crests only feebly develop 

 the intermediate cones, or trefoils. Singularly enough, the supposed north 

 Asiatic ancestors of this phylum are not known. It first appears in the M. 

 J)orsoni of the Pliocene of Europe. 



The Stegodontino' may be distinguished as a phylum confined to Asia, in 

 which the grinding teeth remain brachyodont, short-crowned, although a very 

 large number of cross crests evolve, especially on the posterior grinding teeth. 

 From an early member of this subfamily, perhaps of Middle Miocene time, 

 were given off one or more branches of the elephant and mammoth phyla. 



Rhynehotherium from Mexico. — Extract of letter from Doctor Falconer to M. 

 Lartet, September 12, 1856 :" "At Genoa I saw a cast of a large lower jaw of a 

 mastodon from Mexico, with an enormous hec abruptly deflected downwards 

 and containing one very large lower incisor. The beak is much thicker than 

 in M. (Trilophodon) angus'Udens and larger than in M. (Tetralophodon) longi- 

 rostris. You know that every one (Laurillard, Gervais, etc.), have insisted on 

 the absence of the lower incisors from both of the South American species. 

 The outline of the jaw resembles very much the figure in Alcide D'Orbigny's 

 Voyage, described by Laurillard as M. andium. The specimen is unpublished 

 material and I was therefore only allowed to examine it very cursorily. The 

 Genoese paleontologists had provisionally named it Rhynehotherium, from the 

 enormous development of the beak, approaching Dinotherium." 



The arrangement of the elephant and mammoth phyla is not clear at present, 

 although it appears that four distinct subphyla developed. The first, to which 

 the generic name Loxodonta applies, includes the Pleistocene and recent ele- 

 phants of the African type, which by Falconer and other students of Asiatic 

 forms are supposed to be related to the L. namadicus of the Lower Pliocene of 

 the Siwaliks. The next phylum, Euelephas, by consent of all leading European 

 authorities, begins with E. planifrons of Asia and Europe, Middle Pliocene. 

 It includes E. hysudricus of the Upper Pliocene, passes into the E. meridionalis 

 and E. trogontherii of the Lower Pliocene, and thence into E. primigenius, the 

 woolly mammoth. 



From a Middle Pliocene form, in a stage of evolution similar to that of E. 

 planifrons, it is possible that the peculiarly American mammoths E. columbi 

 and E. imi:crator may have been given off as a side phylum, but this is not 

 yet determined. This leaves the typical elephant, E. indicus, as a related 

 phylum, the ancestry of which has not yet been determined.* 



Thus the Proboscidea divide into at least six great phyla, to which the sub- 

 family designations Elephantinre, Euelephantinw, Loxodontinw, Sfegodontinw, 

 Mastodontin(P, Bunomastodontince, may be given. There are also some reasons 

 for separating the bunomastodonts into three phyla, which might be known as 

 the LongirostrincB. Rhynchoros'trinw, and Brevirostrince, but this may be a 

 somewhat premature opinion. 



1° Charles Murchison : Paleontological Memoirs and Notes of the Late Hugh Falconer, 

 A. M., M. D. 2 vols., 8vo. London, 1868, vol. 11, pp. 74-75. 



