JUNE, 1906. NEw Forms or CONCRETIONS—NICHOLS. 29 
is achain offour sand-calcite balls from Clermont. (Plate XX, Fig. f.) 
This consists of four spheres between 140 and 160 millimeters in 
diameter united into a slightly curved chain 49 centimeters long. 
The spheres where they join interpenetrate for perhaps one-eighth to 
one-twentieth of their respective diameters. Each balls nearly 
spherical with no marked flattening and is simple. The only compli- 
cation of form is an abrupt change in diameter of the spheres giving 
each the external form of a laminated body from which the external 
shell has been half broken away. This is, however, a consequence of 
differing rate of growth for different sides of the sphere and is in no 
wise dependent upon internal structure. These deposits, which are 
associated with mineral springs, are doubtless more or less tufaceous 
in character. 
The sand-calcite concretions of Saratoga Springs, New York, 
tend to form sheets by the coalescence of many ind.viduals and thus 
- much of the material is better described as sandy calcareous tufa 
than as concretionary. The two specimens shown in Plate XXI 
illustrate this phase. These are respectively 15 x 40 and 17 x 20 
centimeters in area and both are from 3 to 6 centimeters thick. Both 
specimens are fragments evidently broken from considerably larger 
sheets. The individual concretions from these sheets are forms 
modified from the sphere by agencies which have p oduced a flatten- 
ing and elongation, so that the simplest form of common occurrence 
is a somewhat flattened ovoid or pear (Plate XXI, Fig. 1) with the 
same appearance of lamination which occurs upon the Paris Basin 
specimens. The larger number of those concretions which unite to 
form a sheet of tufa at Saratoga Springs are much more elongated 
than these pear shapes. Many of these more elongated forms so 
coalesce as to lose their identity and present merely a solid, wavy 
surface. When the individuality is not so completely lost, there 
arise, first, shapes resembling. a long-necked gourd, then, as the 
elongation becomes greater, the flattening becomes greater also, the 
form becomes wavy in both the horizontal and vertical planes and 
deep, strong, longitudinal and occasionally transverse striations 
appear. Thus the elongated individuals forming these sheet-like 
bodies of concretion tend to become flat and more or less curved. 
Besides the tufaceous sheets, separate individual concretions 
are common among the Saratoga Springs material. These show 
little or no flattening and sometimes but little departure of any kind 
from a spherical form. They are frequently heavily striated in a 
meridional direction by deep grooves which come together at two 
