210 DR. C. J. rORSTTH MAJOR ON MIOCENE SQUIRRELS. [Feb. 28, 



exception of Kowalevsky, who, in the same 22ud volume of the 

 ' Palaeontograpliica,' had expressed an identical view, I had supposed 

 that the two inner lobes of upper equine molars are not homo- 

 logous with those of Anchltherium, but are a more modern addition 

 to the tooth. Now ontogeny, according to Klever ', suggests that 

 Kowalevsky and myself are wrong. 



As to the molars of Hydrochoerus, Phacochoerus, and Elephas, I 

 leave them to ontogenists ; and, if I am not mistaken, there is 

 every appearance that we shall not have to wait very long for an 

 answer. 



It may be asked whether the pattern of molars towards which 

 the types of almost all the Orders of Mammalia represented in 

 the Lower Eocene tend is nowhere realized. 



"When I first saw the plates of Marsh's " Discovery of Cretaceous 

 Mammalia," my impression was that the molars figured on plate ii.^ 

 constitute one of the most important discoveries as regards the 

 ancestry of Placentalia, inasmuch as these figures correspond to 

 what I considered, and have been expounding just now, to approach 

 the presumed ancestral form of Mammalian molars. In going over 

 the text, I found that Marsh collocates all these multitubercular 

 teeth in the " aberrant" Order of Allotheria, and states expressly, 

 that " Carnivores, Eodents, and Ungulates appear to be entirely 

 wanting in this unique fauna," and that " a still more surprising 

 fact is the absence of their probable ancestors, unless, indeed, the 

 insectivorous forms are entitled to this important position : many 

 known facts point in this direction" ^. In Part III. of " Discovery 

 of Cretaceous Mammalia" Marsh again states : " These remains are 

 not transitional between Mesozoic and Tertiary forms, but their 

 affinities are with the former beyond a doubt " ''. 



To me it appears, from what we now know of those important 

 fossils called Allotheria, we are not entitled to consider the whole 

 Order as an aberrant one, though there may be, and certainly are, 

 aberrant genera. But, on the whole, the Allotheria are not more 

 aberrant than the Myomorpha, for instance. 



The discovery of the Laramie mammals led to a controversy 

 between their discoverer and another eminent American palaeonto- 

 logist ; but this side of the question has not been taken into 

 consideration, both disputants being agreed in assuming that the 

 multitubercular teeth in question belong to an aberrant group. 

 This aprioristic assumption may have prejudiced the impartial 

 investigation of facts. I cannot enter fully into the question, 

 especially as it would be rash to pronounce too positively on an 



' Ernst Klever, " Zur KenntnisB der Morphogenese des Equidengebisses " 

 (Morphol. Jabrb. xv. 1889, Leipzig, pk. xi.-xiii.). 



^ O. C. Marsh, " Discovery of Cretaceous Mammalia," American Journal of 

 Science, vol. sxsviii. July 1889, plate ii. 



^ L. c. p. 83. 



* " Discovery of Cretaceous Mammalia. --Part III.," /. c. vol. slii. March 

 1892, p. 2.50. 



