1888.] 



Reptilian Character in Mammalian Teeth. 



129 



aluminium. The identity of the position occupied by fluorine in 

 Series II with that of manganese in Series IV perhaps admits of 

 correlation with the occurrence of these elements in plants. 



The table (p. 128) illustrates the preceding observations, and 

 shows the periodic position of aluminium — the element primarily 

 under discussion. For the sake of distinctness the elements generally 

 believed to be essential to the higher plants are printed in capitals, 

 the elements of doubtful necessity in italics, and those which, if they 

 occur at all in plants are certainly accidental, in ordinary type enclosed 

 in brackets. 



Postscript. — Since writing the above paper I have found that the 

 ash from the caudex of another tree-fern (Alsophila australis) contains 

 a very large quantity of alumina. The specimen analysed was from 

 Tasmania. I have also detected more than mere tra.ces of alumina in 

 the ash of the caudex of Dicksonia sqaarrosa. 



IV. " On the Nature and Limits of Reptilian Character in Mam- 

 malian Teeth." By H. G. Seeley, F.R.S., Professor of 

 Geography in King's College, London. Received April 4, 

 1888. 



Approximations between reptiles and mammals have been recognised 

 in many parts of the skeleton.* They are most marked between 

 certain genera and orders of the two classes. The oldest known 

 fossil representatives of both groups certainly approximate closer 

 towards each other in all known parts of skeletons than do the 

 orders which survive ; so it may be a legitimate induction that, in an 

 earlier period of geological time, the characters of both groups were 

 so blended, that there existed neither the modern reptile, which has 

 specialised by losing mammalian attributes, nor the modern mammal, 

 which has specialised by losing the skeletal characters which have 

 come to be regarded as reptilian. The most ancient mammals exhibit, 

 in the known parts of their skeletons, resemblances to Monotremes, 

 Edentates, Insectivores, and apparently Carnivores ; and it is among 

 these orders that the closest correspondence is found, bone for bone, 

 with reptiles. Therefore, if an attempt were made to predict on an 

 inductive basis, the kind of dentition which the earliest mammals 

 which existed would show, it might be expected to be in harmony 

 with the mammalian and reptilian characters of their skeletons. On 

 the same basis it might be suspected that existing mammals, with 



* " Kesemblances between the Bones of typical living Eeptiles and the Bones of 

 other Animals ;" " Similitudes of the Bones, &c.," ' Journal of the Linnean Society, 

 Zoology,' vol. 12, 1874, pp. 155, 296. 



K 2 



