310 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 8, 



M. Lartet, of the Sub-Pyrenean Proboscidea, at Seissan on the Ga- 

 ronne ; together with some of the principal collections at Toulouse. 

 In one or other of these museums I had opportunities of studying all 

 the fossil species hitherto described as having been met with in 

 Europe, together with one fine species of Mastodon discovered by 

 M. Lartet, but which has not yet been published. 



Generic distinctions and nomenclature of the Proboscidea. — 

 Before entering on the special consideration of the British fossil 

 forms, it will be necessary to give some explanation of the principles 

 on which the genera have been limited, and subdivided into sub- 

 generic groups, in order to comprehend the reasons for the nomencla- 

 ture adopted in this communication. A detailed palseontological 

 disquisition would be out of place on the present occasion. Such 

 salient points only will be touched upon as are essential to the eluci- 

 dation of the subject. 



The Proboscidean species, fossil and recent, constitute a large group, 

 embracing at least 25 distinct forms, which are comprised under 

 the three genera of Dinotherium, Mastodon, and Elephas. These 

 genera, regarded in a systematic view, are of very unequal value 

 numerically ; the first being very limited in the number of ascertained 

 species, but defined by well-marked generic distinctions ; while the 

 last two represent a large number of specific forms, which, although 

 their opposite extremes are widely separated, yet are connected together 

 through so complete and natural a series of intermediate specific links, 

 that it has proved difficult to devise good generic characters to di- 

 stinguish them. Putting aside all other considerations of structure 

 and form, the diagnostic marks will be regarded on the present occasion 

 solely as they are furnished by the teeth and jaws. 



(Dinotherium.) — The adult dentition of Dinotherium * is charac- 

 terized by two vertically succeeding premolars and three true molars, 

 five teeth in all, with transverse crenulated ridges closely resembling 

 those of the Tapir ; and by two huge inferior recurved incisors, im- 

 planted in an enormously thickened and deflected beak or prolonga- 

 tion of the symphysis of the lower jaw. Most of the molar teeth 

 present the normal Tapir-like crown-character of two ridges ; but, 

 when the milk- and permanent dentition are taken together, Dino- 

 therium diifers from all the non-elephantoid Pachydermata in the 

 circumstance that the last milk-molar and antepenultimate true molar 

 (being contiguous teeth in the order of horizontal succession) pre- 

 sent a more complex development of three ridges, or, a " ternary- 

 ridged crown-formula" (to use a term which will be found of im- 

 portance in the sequel). Two species only of Dinotherium have, I 

 believe, hitherto been met with ; the one in Europe, and the other 

 in Indiaf. The European species, D. giganteum, occurs in the 



* Kaup, Akten der Urwelt (1841), pp. 22-40. 



t As in the case of the Mastodon of North America, numerous nominal species 

 have been founded by different authors (Kaup, Von Meyer, Eichwald, &c.) upon 

 what would appear to have been merely varieties of the same species, depending 

 on race, sex, &c., as evinced by the comparative size of the teeth. Dr. Kaup now 



