76 
IOWA ACADEMY OF SCIENCES. 
characteristics until in the common form the presence of cal- 
cite would not be suspected, and the surface of the cones, 
instead of showing clearly the individual calcite needles sharply 
terminating, has only a peculiar crinkled or roughened appear- 
ance. 
Owing to the very strong crystalizing force known to be 
possessed by calcite, so powerful an influence is exerted by this 
substance in solution, which is manifestly at the point of satu- 
ration, though distributed rather sparingly through the clay 
layers, that even the clay is pressed into the form assumed 
under normal conditions by the calcite. The process and results 
are not unlike those which have taken place in certain sand- 
stone beds in central France, in which calcic carbonate has 
crystalized in the sand, and large perfect models of sand 
cemented by lime are found, having the well formed and char- 
acteristic crystalographic faces of calcite. 
TWO REMARKABLE CEPHALOPODS FROM THE UPPER 
PALEOZOIC. 
BY CHARLES R. KEYES. 
There have been recently discovered in the coal measures of 
Mississippi basin some excellently preserved remains of Cepha- 
lopods, which are remarkable on account of the huge size 
attained. Both are representatives of the retrosiphonate Nau- 
toidea; but one is a member of the most closely coiled end of 
the series, while the other is a perfectly straight form. The 
former belongs to the genus Nautilus and the latter to 
Orthoceras. 
The first group comprises a series of shells, which were 
obtained from the upper coal measures at Kansas City, Mo. 
Several unusually fine specimens are the property of M. S. J. 
Hare of that place, and others are in the possession of other 
collectors. The form was originally described by White* 
as Nautilus ponderosus, the diagnosis of which is essentially as 
follows: 
*U. S. Geol. Sur., Nebraska, p. 236, 1872. 
