383 
PALEONTOLOGY OF NEW YORE. 
feature of the direction of the aperture is inferred from the lines of growth 
and the direction of the ornamentation of the test. The crenulations are , 
preserved as fine, rounded ridges and striae, along the internal mould of the 
walls of the air-chambers. 
Air-chambers frequent, regular, becoming numerous toward the apex, 
having a depth of ten mm. near the grand chamber, and of one mm. near 
the apex. Septa smooth, with a very slight concavity, equal to an arc of 
about 60°. Sutures straight, and at right angles to the spiral axis. 
Siphuncle near the ventral side, small in its passage through the septa; 
having a diameter of six mm. where the tube has a ventro-dorsal diameter 
of forty-five mm. 
The test has a thickness of about one mm. on the outer volution. Surface 
marked by irregular, lamellose, undulating lines of growth, which slope in a 
retral direction, oblique to the spiral axis of the tube. The ornamentation 
consists of strong, transverse, prominent, plicate, foliate expansions of the 
test, inclining toward the aperture, and having an elevation of about twenty- 
seven mm. on the outer volution, growing less prominent and more finely 
plicated toward the apex. These expansions are quite regularly plicate, and 
present surface-markings similar to the general surface of the tube. The 
folds or plications are continued along the tube, forming rounded, revolving 
ridges. The sinus in the strise and ornaments of the test is rounded, and 
has a width equal to twice the depth. 
The internal mould is annulated from the strong transverse expansions 
of the test, and shows the furrows and ridges of the crenulations, with those 
of the test. Sutures not impressed. 
One specimen, nearly entire, constituting about one volution and a half, 
has a length of 600 mm., with a diameter of seventy-five mm. near the aper¬ 
ture, and measures 210 mm. from the ventral margin of the aperture across 
the volutions. 
This species is distinguished by its size, the curvature of the tube, the apical 
angle, and the prominence of the ornamentation. The apical portion differs 
from G. trivolve in its more rapidly enlarging tube and marked characters of the 
