204 DR. C. J. FORSYTH MAJOR ON MIOCEXE SQUIRRELS. [Feb. 28, 



considered by Schlosser himself to be a Lemurid ', and Osborn" had 

 placed both of thein amongst the PseudolemuridcT. AVhilst fully 

 agreeing \\ith Schlosser in his main conclusions, for reasons ^^hich 

 I shall discuss elsew here, I am again at a loss to see w hat trituber- 

 culism has to do \\ith the matter \ and \\ ould put but one question : 

 How comes it that both Protoadapis and Ph-slni/fqiis, which are 

 indeed the most ancient types of Rodents hitherto known, show 

 the so-called heel of inferior uiolars in such a perfect condition * in 

 spite of tritulierculism, which 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 pi'eceding 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 " Sciuruhe," 

 amongst which we meet with the most j)rimitive 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. J have tried to show that th(,'y have failed to do so, and in 

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

 polybunous form, and that the real tritubercular pattern is a more 

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

 cardinal point to be established is to show, that the moi'e complex 

 forms, which hi the Lower 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 . Braehijtioiifi/ is the more primitive, the more geiU-ralized condition 



of molar form, and so is 



2. Bunodontj/, as o/>jiosed to Lophod.ontij (or Zyyodonii/, which is 



the same thinff). 



3. The more hrachgclout a molar is, the 'more mnltitrdierci'lar it is, 



or, let us sat/, jioli/hunous. 



4. 2'he transformation, I'iz., the reduction and simplification, pro- 



' M. Schlor'>er, " Die Affen, Lemuren, Chivopteren, Insectivoren etc. des eiiro- 

 piiischen Tertiars, etc." Pt. I. Wien, IS.**", p. 47. 



- Henry Fairfield 0>ho]U, "A Review of tlie Cernavsian ilarunialia " (I'roc. 

 Pliil. Acad. >'at. .Sci., Mnj (jtb, ISltO, pp. .">.'., .".Ci. 



' " Das-s aber die.ser Tjpus (/. e. Trituberciilartypus) auch den Ausgangspunkt 

 fiir die oberen Molaren der Xager darstellt. erselien wir darau.';, dasa er sioh bei 

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

 p. 240.) 



■* Lemoine, /. o. pi. x. 



