1893.] NEW YORK ACADEMY OF SCIENCES. 187 



work in this direction, and stated that be hoped to publish 

 before long, a complete discussion of all existing observations 

 of close i^olars. 



April 10, 1893. 

 Stated Meeting. 



President Bolton in the chair, and thirteen persons present. 

 The President announced the death of M. Alphonse De 

 Canuolle, an Honorary Member of the Academy. 



« 



BIOLOGICAL SECTION. 



Prof. H. F. OsBORN, on "The Evolution of Teeth in Mammalia 

 in Its Bearing Upon the Problem of Phylogeny," reviewed the 

 recent researches and theories of Kixkenthal, Rose and Tacker 

 upon the formation and succession of the dental series in mam- 

 malia and pointed out that especially in marsupials, cetaceans 

 and edentates (with other placentates), the existence of two 

 series of teeth was now abundantly proven, as well as the fact 

 that homodont forms were derived from early helerodont. He 

 then showed that recent discoveries demonstrated that in 

 marsupials, teeth of the second series might be interposed in 

 the first sei'ies — to explain the typical dentition of such forms 

 as Didetphys. This transposition enables a comparison of 

 dentition of marsupials with that of Jurassic mammalia (= i, 

 4> c. 1, p. 4, m. h). It was further noted that the triconodont 

 type (as Amphileste.H) was probably the hypothetical point of 

 divergence of jjlacental mammalia. As to the form of crowns 

 the theory (Kiikenthal — Rose) that complex mammalian types 

 were made by concrescence of simple reptilian cusps, was uj^on 

 the evidence of the Jurassic mammalia, shown untenable— as 

 well as the converse theory that cetaceans have derived hoiuo- 

 dynamous forms b}^ the splitting of the cusps of triconodont. 



Dr. Bashford Dean, in "Contributions to the Anatomy of 

 DinichJhy.-^," correlated the parts of this Devon-Lower Carboni- 

 ferous Arthrodiran with those of Coccosteus. Notes were made 



