1893. } NEW YORK ACADEMY OF SCIENCES. 187 
work in this direction, and stated that he hoped to publish 
before long, a complete discussion of al] existing observations 
of close polars. 
April 10, 1893. 
Sratep MEETING. 
President Botron in the chair, and thirteen persous present. 
The President announced the death of M. Alphonse De 
CanpoLie, an Honorary Member of the Academy. 
BIOLOGICAL SECTION, 
Prof, H. F. Osporn, on “The Evolution of Teeth in Mammalia 
in Its Bearing Upon the Problem of Phylogeny,’’ reviewed the 
recent researches and theories of Kukenthal, Rose and Tacker 
upon tha 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 homedont 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 series—to explain the typical dentition of such forms 
as Didelphys. This transposition enables a comparison of 
dentition of marsupials with that of Jurassic mammalia (= i, 
4,¢e.1, p- 4,m. 8). It was further noted that the triconodont 
type (as Amphilestes) was probably the hypothetical point of 
divergence of placental mammalia. As to the form of crowns 
the theory (Kukenthal—Rose) that complex mammalian types 
were made by concrescence of simple reptilian cusps, was upon 
the evidence of the Jurassic mammalia, shown untenable—as 
well as the converse theory that cetaceans have derived homo- 
dynamous forms by the splitting of the cusps of triconodont. 
Dr. Bashford Dean, in ‘‘Contributions to the Anatomy of 
Dinichthys,’”’ correlated the parts of this Devon-Lower Carboni- 
ferous Arthrodiran with those of Coccosteus. Notes were made 
