204 DE, C, J. rOKSYTH IIAJOE Oy MIOCEXE SQriEnELS. [Feb. 28, 



considered by .Schlosser himself to be a Lemurid \ and Osborn' had 

 placed both of them amongst the Pseudolemuridje. AVhilst fidly 

 agreeing with Schlosser in his main conclusions, for reasons which 

 [ shall discuss else\\ here, I am again at a loss to see w bat trituber- 

 culism has to do with the matter \ and would put but one question : 

 Ho« comes it that both Pt-otoadapis and PlesHahtpis, which are 

 indeed the most ancient types of Eodents hitherto known, show 

 the so-called heel of inferior molars in sucli a perfect condition ' in 

 spite of trituberculism, \\ hich considers these parts as a late addition 

 to the original triangle of inferior molars ? 



I have declared myself opposed to the tritubercular theory, but 

 have limited my remarks hitherto merely to criticism, though 

 occasionally I offered some positi\e argument in favour of an 

 hypothesis which is in many points the very reverse of the pre- 

 vailing theory. It remains now for me to justify the position I 

 have taken with regard to it ; what I am going to say is partly a 

 summing up of preceding remarks, and partly embraces a far \nder 

 field, and will, 1 have no doubt, meet with some opposition. 



Xo better starting-point could be chosen than the " Seiuruhe," 

 amongst which we meet with the most primitive form of molars of 

 this low order of Mammalia. 



- The adherents of trituberculism assert that they have proved 

 the Mammalian molar to be traced back to a more and more simple 

 form. I have tried to show that they have failed to do so, and in 

 my turn assert that the molar of Placentalia can be traced to a 

 polybunous form, and that the real tritubercular pattern is a moi-e 

 specialized secondary stage. So that, as a matter of course, the 

 cardinal point to be established is to show, that the more complex 

 forms, which ui the Low er Eocene as well as in the recent period 

 are found side by side with the simpler forms, trituberculate or 

 otherwise, are indeed the primitive, the more generalized type. 



To prove my assertion, I start from five assumptions : — 



1. Brctfhydont;! is tJie more primitive, the more generalized condition 



of molar form, and so is 



2. Binwdonti/, as opposed to Lopliodontii ("*' ^I/i/odontt/, which is 



the same thing). 



3. The more brachi/dont a molar is, the more mxdtituhercular it is, 



or, let vs sag, polgbunoits. 

 ■i. The transformation, vi:., the redxction and simplification, pro- 



' M. Schlosfier, " Die Affen, Lemuren, Chiropteren, Insectivoren etc. des eiiro- 

 piiischeii Tertiiirs, etc." Pt. I. Wien. 1887, p. 47. 



- Henry Fairflelci 0.-<born, "A Review of the Oernaysian Mammalia " (Proc, 

 Phil. Acad. Nat. Sci., May Gtb, 1800, pp. r.j, r.(i). 



■' " Dass aber die.ser Typus (/. c. Trituberculartypiis) audi den Ausgangspunkt 

 fiir die oberen Molaren der Nager darstellt, erselieu wir daran-;, dass er sich bei 

 Sciiiriis sogar noch bis in die Gegenwart ziemlich rein erlialten hat." (L. c, 

 p. 240.) 



^ Lemoine, /, c. pi. x. 



