210 
PAL JEON TO LOGY OF NEW YORK. 
CoNULARIA CREBRISTRIATA. 
PLATE XXXIII, PIGS. 8, 9; and PLATE XXXIV A, FIG. 5. 
Comdana crebristriata, Hall. Illustrations of Devonian Fossils: Pteropoda, plate 29, figs. 8, 9. 1S76. 
Form comparatively slender, regularly pyramidal, with a quadrangular base. 
Transverse section quadrangular with the sides unequal, the proportions 
being about as two to three; a part- of this inequality is owing to a 
slight distortion through a compression of the specimen. Angles of the 
pyramid marked by a very distinct groove, which is crossed by the surface 
strife. Faces of the pyramid somewhat concave, with scarcely a defined 
median groove, which in nowise affects the continuity of the transverse 
strife. Aperture oblique. The summit has apparently been truncated by 
a septum. 
Surface marked with very fine salient, distinctly nodose or pustulose strife, 
which curve gently forward on the middle of the face; not interrupted by 
the median depression, and somewhat gently recurved over the convexity 
bordering the furrows at the angles of the shell, and continuous across 
the depression; spaces between the strife about twice as wide as the 
strife, and apparently free from ornamentation. The ornaments of the 
surface are only visible under a lens. 
In some parts of the shell the strife are much more closely arranged than in 
others—an evidence of retardation in growth. In one specimen the strife 
of the earlier growth, for at least one-third of the length of the shell, are much 
coarser than the later growth, and the change from the one to the other is 
quite abrupt. 
This species is more slender in its mode of growth than C. undulata , and the 
transverse strife finer, but the character of the ornamentation is precisely 
similar. Two specimens only, of this form, have been observed; one of these 
is a mould of the interior (the shell having been dissolved), which preserves 
the general form of the species; the other is, in part, an impression of the 
exterior in soft shale, preserving a portion of the interior surface of the shell. 
