210 PALEONTOLOGY OF NEW YORK. 



CoNULARIA CREBRISTEIATA. 



PLATK XXXIII, FIGS. 8, 9; AND PLATE XXXIV A, FIG. 5. 



Conularia crebrtstriata. Hall. Illustrations of Devonian Fossils : Pteropoda, jilate 29, figs. 8, 9. 1876. 



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 

 striae. Faces of the pyramid somewhat concave, with scarcely a defined 

 median groove, which in nowise affects the continuity of the transverse 

 striae. Aperture oblique. The summit has apparently been truncated by 

 a septum. 



Surface marked with very fine salient, distinctly nodose or pustulose striae, 

 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 striae about twice as wide as the 

 striae, and apparently free from ornamentation. The ornaments of the 

 surface are only visible under a lens. 



In some parts of the shell the striae are much more closely arranged than in 

 others — an evidence of retardation in growth. In one specimen the striae 

 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. 



Tbis species is more slender in its mode of growth than C. undulata, and the 

 transverse striae 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. 



