202 BK. C. J. T-OUSYTTT ^rAJOB ON MIOCEXE SQFTBRELS. [Feb. 28, 



very small details. The only inference I Mish for the present ^ to 

 draw from this fact and its consequences is, that Prof. Fleischmann, 

 too, is on his way to become an opponent of trituberculism. 



It would appear that the Allotheria, the Multitubercnlata 

 Knr' e£o)(()»', ought to have been a stumbling-block for the theory. 

 Eut this is not the case ; they have been simply pushed aside on 

 account of being an aberrant order. Nevertheless, I shall refer to 

 them later on. 



The dentition of Rodentia has as yet not much been dealt with 

 in relation to the tritubercular theory. Scott was the first to 

 touch upon the question, when describing the Plesiardomys sciu- 

 roiUeii, S. & O., from the Uinta formation", considered by him to be 

 " one of the oldest, if not the very oldest known form of rodent." 

 Owing to the importance which for this reason is attributed to the 

 fossil, I must dwell upon the subject at some length. Scott has 

 shown to his own satisfaction and to that of others that the 

 superior molars of Pleslarctomns scmroides " are plainly of the tritu- 

 bercular pattern,"' and that " the inferior molars show the anterior 

 triangle of three cusps with a talon behind, or \\ Iiat Cope has termed 

 the tuberculo-sectorial molar." It might be questioned at once 

 whether this specimen, the teeth of which are much worn according 

 to the author's own assertion ^ and according to what appears from 

 the diagram ' and the figures °, is a proper object from which to draw 

 such important inferences. I fail to see in its molars anything 

 else than the usual Sciuromorphine type, which I agree with 

 Scott in considering as a ^ery old one. I have myself pointed 

 this out twenty years ago in some fossils (Scim-ns spectahiUs) from 

 the Eocene of Egerkingen ", which, are rather older than the Uinta 

 formation. The Uinta beds are considered by Zittel " to be Lower 

 OHogocene, whilst the Bohnerz of Egerldngen has important rela- 

 tions with the oldest Eocene of Europe (Eeims) and America 

 (Puerco).\ On the other hand, this type is still in existence, and 

 w idely spread among living Sciuromorpha. 



i think that Scott is mistaken in what be considers to be the 

 homologies, in tlie lower molars of Plrsiarctoim/s, of the anterior 

 triangle of Unguhxtes, Creodonts, and Lemuroids. This anterior 

 triangle is formed, as clearly shown by unworn molars of most of 

 the Sciuromorpha, In' the antero-external and antero-internal 

 cusp (the jirolocoiiid and metaconiil according to Osborn's no- 



1 See also \V. B. Scott, " The Evolution of the Premolar Teeth in tlie Mam- 

 mals" (Proc. Ac. Niit. Sci. Philad. 1802, p. 410). 



- William B. Scott and Henry Fairfield Osborn. " The Mammalia of (he 

 Uinta Formation " (Traus. Anjer. Philos. Soc. n. s. vol. xvi. pt iii Aug ''O 

 1880, pp. 47G-478). is--. 



^ L. c. p. 477. 



' P. 476. 



' PI. xi. 1 r, ] t!. 



" Forsyth Major, •' Nageriiberreste aus Bolinerzen Siiddeutschlands und der 

 Schweiz." 



' ' Handbiich der Palaontologie, T. Paliiozoologie,' IV. Band, 1892, p. 66. 



" L. Riitiraeyer, "Die Eociine Siiugethierwelt voii Egerkingen," Abhandl. 

 schweiz. palaont. Ges. xviii. 1801. 



