426 PALEONTOLOGY OF NEW YORK. 



GLYPTOCARDIA, n. o. 

 Glyptocardia speciosa. 



PLATE LXX, FIGS. 2-» ; AND I'LATE LXXX, FIG. 10. 



Avicula speciosa, Hall. Geol. Sui-v. N. Y., Rep. Fourth Dist., p. 243, t. 106, figs. 1, la. 1S43. 

 Cardiola speciosa (Hall), 8. A. Millkk. Cat. Am. Pal. Foss., p. 186. 1877. 



" " " Pal. N. Y., vol. V, pt. 1. Plates and Explanations: PI. 70, figs. 2-9. 18t^3. 



Compare Venericardiuia retrostriatum, v. Been. Ueb. Ammon, p. 50. 1832. 



" Oardioia refrusirjoto (v. Bucu), Kkyskrling. Petschora-Land, p. 254, pi. 11, fig«. 3-3c. 1846. 

 " " " " Sandbergbr. Vei-stein. Nassau, p. 270, pi. 28, figs. 8, 9, 10. 1850- 



1856. 

 " " t " " var. Boheinica, Barrande. Syst. Sil. Bohfime, pi. 181, fig. II, 



1-10. 1881. 

 " Cardium retrostriatum, " Qbinitz. Grrauwackenform. in Sachsen, 11, s. 47, taf. 12, fig. 7. 

 " " palmatum, Goldfuss. Peti-ef. Germ., p. 217, t. 143, fig. 7. 1837. 



"' " " " F. A. RcKMBR. In Dunker and Von Meyer, Pateontographica, 



B(l. Ill, a. 26/, taf. 4, figs. 11, 12. 18!)0. 



Shell small, broadly elliptical or sub-circular, sometimes broadly obovate ; length 

 about one-fourth greater than the height; basal margin regularly curving, 

 somewhat obliquely truncate from the beak to the posterior extremity. 



Valves regularly convex below, becoming gibbous in the middle and 

 descending thence to the beaks. 



Beaks anterior to the middle, closely incurved and directed forward. 



Surface marked by from twelve to fifteen plications ; those on the body of 

 the shell broad, flattened along their upper surface and sculptured by promi- 

 nent arching lamellose striae, which are sometimes raised into nodes. The 

 interspaces are finely, and inconspicuously, transversely striated. 



Numerous specimens measure 7 mm. in length and 5 mm. in height. The 

 smallest specimen observed has a length of 3.5 mm. and a height of 2.5 mm. 

 The largest individual in the collection has a length of 10 mm. 



The specimens are subject to considerable variation in form, chiefly owing 

 to the direction of the pressure from the enclosing matrix. The plications 

 also vary in width and prominence, and in the degree of sculpturing. 



This species has a wide range in New York, occurring in the Hamilton 

 group, Genesee slate, Portage and Chemung groups. It is probably identical 



