370 
PALAEONTOLOGY OF NEW YORK. 
Test thin, with a thickness of .75 mm. over the chamber of habitation, and 
of .25 mm. on the apical portion of the tube. Surface marked by fine, irreg¬ 
ular, lamellose lines of growth, crossed by irregular, longitudinal striae. The 
ornamentation consists of regular, prominent, sharp, foliate ridges or expan¬ 
sions of the test, slightly inclining toward the aperture, and are more distant 
along the middle portions of the tube; becoming gradually more numerous 
and less prominent toward the apex and aperture. On one specimen the 
distance between two expansions is ten mm., and on another five mm., 
varying with the age or size of the individuals. Sometimes the elevation 
of the folds measures nine mm., but it is only on the larger specimens. 
Sinus very distinct, affecting the surface-markings and transverse costre; 
angular near the apex, becoming deeper and rounded toward the aperture. 
The internal mould preserves traces of the furrows of the crenulations, the 
surface-markings and low annulations corresponding to the prominent, trans¬ 
verse expansions of the test. The ventral side of the tube is slightly flat¬ 
tened along the portion covered by the sinus in the striae and ornaments. 
A small example, nearly entire, has a length of 193 mm., with a diameter 
of thirty-one mm. at the aperture, and shows about forty-five of the trans¬ 
verse costae. The largest individual observed has a diameter of^thirty-five 
mm. at the aperture. 
This species resembles C. aimulum, but is characterized by its lesser curva¬ 
ture of the tube, larger apical angle and more distant, regular and prominent 
transverse folds, forming the ornaments of the test. It is a common and 
well-marked species, and may be recognized, even from small fragments, by the 
distance and prominence of the transverse expansions, which resemble those of 
G. Matheri, but are much more frequent. In the Schoharie grit the specimens 
are mostly very imperfect and fragmentary, but the limestones above furnish 
well-preserved individuals, which retain their natural form and proportions 
Formation and localities. In the Schoharie grit, in tike counties of Schoharie 
and Albany, and in the limestone of the Upper Helderberg group, at Scho¬ 
harie, N. Y. 
