510 Proceedings of Societies. [Angust, 
which are characterized by a prolonged growth of the incisors, having 
enamel only on one side. The incisors in the form under consideration 
have enamel on the front and back, but not on the side. The characters 
of the other teeth were given as they exist in the genera Calamodon 
and Ectogamus, in each of which two species are known. The relation- 
ship established by these genera between the Edentata and the other 
mammalia was alluded to. These forms are both from the Wasatch beds 
of New Mexico. The name Tzniodonta was proposed for the group 
indicated. 
Dr. Koenig called attention to a mineral, probably tantolite, from 
North Carolina. he distinction between columbite and tantolite is 
difficult to determine. The peculiarities discovered by analysis were 
described at length and the distinctive characters indicated. Its specific 
gravity is 5.8. 
April 4th. Prof. Burt G. Wilder, of Cornell University, made a com- 
munication upon the anatomy and development of the brain in fish-like 
vertebrates. After considering the taxonomic value of the brain, he 
spoke of the investigations of Huxley, Owen, and the continental natu- 
ralists, dwelling particularly upon the causes of the great inaccuracy M 
the figures of fishes’ brains contained in the text-books. He had en- 
deavored to ascertain how far the brains of fishes might be homologized 
with the typical brain described and figured in diagram by Huxley. 
The differentiation of the three typical cerebral vesicles was described, 
and the fact stated that while the typical description applies to all the 
higher vertebrate brains, neither the lateral ventricles nor the foramen 
of Munroe had been observed in the brains of fishes until recently found 
by Professor Wilder in the gar-pike. He had since found them in the 
lamprey and the hag-fish, in several sharks and skates, in sturgeons, m 
the spoon-bill sturgeon, in the mud-fish or Amia, and in several typical 
bony fishes. He showed in what way the nearly solid front mass of the 
adult shark’s brain is formed from a thin-walled vesicle in the embryo. 
The structure of the brain in ganoids and teleosts was described, and 
the distinction indicated that in the latter, although the lateral ventricles 
and the foramen of Munroe are present, they are so small as to be = 
most invisible. We are forced back, therefore, in searching for the dis- 
tinctive character of the ganoid brain, upon the chiasma of the optic 
nerves of Miiller. In considering the taxonomic value of these pert 
ters, the belief was expressed that the structure of brains will be foun 
to be less dependent upon external modifying circumstances than are 
other parts of the animal organization. val 
In conclusion, Professor Wilder exhibited and described the bram 3 
Chimæra, and indicated its relations to the other groups spoken of. ý 
regarded the brain as presenting characters intermediate betwee? : 
sharks and skates, the ganoids and the batracbians with Lepidosteu® 
Professor Cope called attention to the entire novelty of cert . 
observations made by Professor Wilder, and suggested the direction 
rtain of the 
