218 Oldfield Thomas, Das Milchgebiss der Sugetiere. 



But nevertbeless this does not prevent my believiug in such things 

 as persistent gewordene Milchzhne", for, in the case of the Rhino- 

 ceros, I have stated (p. 451) originally, on the authority of Mr. Ly- 

 dekker^), that the same tooth is a persistent milk-tooth, and this 

 opinion is only confirmed by a renewed exaraination of the specimens 

 in the British Museum. The anterior tooth comes up with, is similar 

 in height and structure to, and is obviously serially homologous with 

 the other milk-premolars, but is succeeded by no permanent" tooth, 

 and is persistent until a comparatively hite period of the aniraals life. 



The same tooth, P^, is stated by Dr. Schlosser (p. 88u.91) to 

 have changed in the Creodonts, although it does not do so either in 

 the Carnivora or Insectivora. This statement is an excessively inter- 

 esting and important one, and I should be grateful if Dr. Schlosser 

 would give his authority for making it, with references to published 

 figures or descriptions. I have myself been unable to find any evi- 

 dence either for or against it, 



The first part of the sentence of Dr. Schlosser 's paper quoted 

 above refers to the view that the anterior cheek-teeth of the Elephant 

 are also persistent milk-teeth, a view advocated by Dr. Falconer, 

 supported by Mr. Lydekker, and amply borne out by an exami- 

 nation of the magnificent series of fossil Proboscidean remains in 

 the Geological Departement of the British Museum. Dr. Schlosser's 

 opinion is that die Milchzhne werden einfacher und schwcher, 

 weiter gehen sie in einem immer frheren Stadium verloren, und zu- 

 letzt bleiben sie ganz aus; an ihrer Stelle erscheinen sofort die 

 definitiven Pr.", but it appears to me to be perfectly evident that the 

 milk-teeth in passing onwards through Mastodon to Elephas steadily 

 become larger, more complex, and more similar to the many-crested 

 anterior teeth of the living Elephants, with which they seem to be 

 unquestionably homologous 2). On the other band the teeth of the 

 true permanent series, which succeed the earlier set in Mastodon and 

 Elephas planifrons, always remain small and simple, and are clearly 

 those that are lost in the later and more highly specialized forms. 

 Here again we have a clear case of persistent gewordene Milch- 

 zhne". 



The homologies of these particular teeth may appear to be 

 merely a matter of detail compared to the general questions involved, 



1) J. As. Sog. Bengal. XLIX. p. 135. 1880. 



2) Compare for example the figures given by Mr. Lydekker (Palaeonto- 

 logia Indica, ser. 10, vol. I, pl. XXXVII, figs. 6 and 8) of the milk and perma- 

 nent P* of a young specimen of ElcpJtas clifti. Fig. 6 is the permanent tooth, 

 extracted from the bone, and Fig. 8 the milk -tooth still in situ above it. 

 That the latter rather than the former is homologous with the complex 

 Elephant's anterior tooth is obvious at the first glance. This specimen (or 

 rather its cast) is referred to as M. 34212 in Cat. Foss. Mamm. B. M. IV. 

 p. 80. 



