188 PALJSONTOLOGY OF NEW-YORK. 



Fig. 1 g. The punctate surface shown where the shell is exfoliated. 



Fig. 2. The dorsal valve of a well-preserved specimen. 



Fig. 2 c. Profile of strias, showing the clovations and fiat surfaces between them. 



Fig. 3. A ventral valve, probably, of this species. 



The specimen, Plate xviii, fig- 3 a, presents characters which are somewhat 

 intermediate to this one and S. pimciuUfera ; the surface, . when partially ex- 

 foliated, showing the punctate character represented in fig. 3 A of same plate. 



Geological position and localny. In the shaly limestone of the Lower Helderberg 

 group : Helderberg mountains; Schoharie, Hudson, Catskill, etc. 



Stropliodoiita puiictulifera. 



Plate XXI. Fio. 4 ; and Plate XXIII. Fig. 4-7. 



Strophometia punctuli/era : CoNiiAD, Ann. Report on the PalsBontology of New-York, 1838, p. 117. 

 — — Vanuxkm, Geol. Report Third District of New- York, 1843, pa. 122, fig. 



5. englypha : Conbad, Ann. Report Palaeontology of New- York, 1841, p. 36. 



Shell subsemicircular, about four-fifths as long as wide. Ventral valve 

 concave : beak not projecting beyond the hinge. Dorsal valve concave 

 near the umbo, very convex near the middle : beak not elevated above 

 the cardinal margin ; sides somewhat contracted below the extremities 

 of the hinge. Hinge line straight, nearly or quite equalling the greatest 

 width of the shell, finely crenulated. Area narrow, linear, vertically 

 striated. Foramen nearly closed, with a narrow prominent callosity 

 along the centre. 

 Surface marked by strong sharp stria?, which increase by bifurcation and 

 interstitial addition, becoming rapidly more numerous and finer towards 

 the margins, and are distinctly punctate in the best preserved speci- 

 mens. 



The Strophomena punctulifera is described by Mr. Conrad as " Shell with the 

 "^ upper valve deeply concave : radiating strife very numerous, prominent, angu- 

 " lated, each with a series of very regular small elevated punctaj. Length two 

 " inches. Locality, Helderberg mountains." 



The specimen, fig. 4, Plate xxi, was regarded by Mr. Vanuxem as this species; 

 and it appears to be identical with a strongly striated one in the Pcntamerus lime- 

 stone, which I have placed under the same designation. The striae, even in those 

 scarcely exfoliated, are marked by one or two rows of elevated pustules, which are 



