LOWER HELDERBEEG ROCKS. 347 



PTEROPODAL!]. 



The strata of the Lower Helderberg group have furnished two species of 

 CoNULARiA which appear to be distinct from any in the preceding forma- 

 tions. The CoNULARi^, however, like all the phosphatic fossils, offer so 

 little variety of form and surface ornament that the diiferent species are 

 not readily distinguished*. 



Conularia pyraiuidalis ( n. s.). 



Plate LXII A. Fio. 1 a - d. 



Shell pyramidal, quadrangular, length about two and a half to three times 

 the width at the base ; apex rounded, smooth ; sides a little convex ; 

 sulci at the angles narrow, abrupt, a faint longitudinal depression along 

 the middle of each side ; transverse ridges bending upwards towards 

 the angles, very slightly near the base and more abruptly towards the 

 apex, continuous across each face, being slightly depressed in the 

 middle, and meeting at the longitudinal suture at about the same angle 

 as in the middle of each side ; about fifteen or sixteen in the space of 

 three lines, sometimes more crowded at intervals near the base ; inter- 

 mediate spaces marked by longitudinal striae, of which there are more 

 than twice as many, in an equal space, as of the transverse ridges : 

 crests of the transverse ridges marked by short nodes or granules at 

 the junction of the longitudinal striae. 

 This species resembles the C. trentonaisis in general form; but the transverse 



ridges and longitudinal strife are generally finer in that species, which, however, 



presents considerable variation in these characters. 



Notwithstanding that several of the specimens are broken across, they do not 



show any septa or other internal divisions; and the two specimens from the Trenton 



• That the phosphatic shells exhibit so little variety, compared with the calcareous shells, is a fact that 

 presents an interesting analogy to the few modifications of mineral forms in the phosphates, and the great 

 multiplicity of form in th» carbonates, of lime. 



