152 
making sections of them and examining them by means of 
the microscope; as the mode of formation of such concretions 
would doubtless throw some light upon the subject of the 
growth of the shells of Mollusca and the occurrence of what 
are known as “interglobular spaces” in the dental structures 
of the higher animals; which he was at present engaged in 
investigating. 
Pror. T. Eaurston exhibited two large crystals of 
Diamond, belonging to Tiffany & Co. One was a hexoc- 
tahedron, very much rounded, in which the lines of out- 
line of the faces of the rhombic-dodecahedron and trigonal 
tris-octahedron were very prominent. Its weight was two 
carats, and it was remarkable for its clear color and regulari- 
ty of shape. The second crystal was octahedral in form and 
showed the interpenetration of other crystals composed of the 
rhombic-dodecahedron and octahedron, The weight of this 
specimen was a little more than two carats and was remarka- 
bly clear. 
The president, Dr. J. S. Newserry, exhibited a series of 
specimens of Fossil Fishes from the Devonian Rocks of Ohio. 
These embraced eighteen species, representing several new 
genera, some of which were of remarkable character. 
Perhaps the most common of the great ganoids of the 
coniferous, is Macropetalichthys, of which the cranium was 
composed of a series of polygonal plates covered with a 
stellate tuberculation, resembling in this and other respects 
the Asterolepis of the Old Red sandstone of Scotland, and 
attaining about the same size. No teeth had been found 
with the cranium of this fish, and it was probably soft- 
mouthed like the sturgeon. 
Onychodus, a still larger ganoid, nearly as common in the 
Corniferous Limestone, was well provided with teeth. This 
fish had a scaled body, head composed of a great number of 
bony plates, and both maxillaries and mandibles set with 
teeth. The most singular feature in this fish was a crest of 
large teeth, seven in number, forming a single row, set 
