ITS DISPUTED AFFINITY". 451 



Plagiaulax were constructed, and, having determined this, to 

 supply the rest empirically by comparison with known forms, 

 using at the same time rational analysis where it could be 

 applied, e.g. to the condyle. The case is of sufficient interest 

 and importance to test the sufficiency of the respective modes 

 of analysis. 



In the general remarks appended to my former communi- 

 cation, I called attention to the contradictory bearing of the 

 dental system of Plagiaulax upon the assumption that the 

 earliest Mammals had the full complement of teeth. To that 

 may be added the further evidence of specialization, in the 

 analogy of its mandible with that of the Aye- Aye, one of the 

 most exceptional of Mammals. If we cast a glance over the 

 instructive table given in Lyell's ' Supplement ' (page 23), 

 and reflect on the interpretation of the hiatus between the 

 Upper Oolitic beds and the ' Sables de Bracheux,' how vast the 

 interval in time by which they are separated, and how modern 

 in comparison the earliest of Tertiary Mammals ! If, on the 

 other hand, Plagiaulax be regarded through the medium of the 

 view advocated with such power by Darwin, through what a 

 number of intermediate forms must not the genus have passed 

 before it attained the specialized condition in which the 

 fossils come before us ! What a variety of Mammals may 

 we not hope to disentomb from the buried Oolitic fauna, 

 should Mr. Beckles resume his explorations, or another 

 Beckles take his place ! 



The remote antiquity of the fossil as a mammalian genus 

 must alone invest the discussion of its affinities with an in- 

 terest which will prevent the question from resting in its 

 present disputed state. Other palaeontologists will examine 

 the evidence, and give their verdict. Mr. Beckles's speci- 

 mens have long since passed out of my hands ; and I have 

 deferred my rejoinder in the expectation that they might ere 

 now have found their way into some public collection, where 

 I could have again submitted them to examination and com- 

 parison ; but, as that has not yet taken place, I have thought 

 it full time to reply, lest my silence should be construed into 

 a tacit acquiescence in the carnivorous character attributed 

 to Plagiaulax, which I do not accept — nor the reasoning on 

 which it is founded. 



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