Ferruginous Sand Formation. 131 



CONUS. 



C.gyratus. (S. G. M.) PI. X, fig. 13. 



This fossil ©ccurs in the calcareous strata of the Southern states 

 but is rare. 



BALANUS. 



S. peregrinus. (S. G. M.) PI. X, fig. 5. 

 Occurs in the calcareous strata. 



SPATANGUS. 



S. ungula. (S. G. M.) PI. X, fig. 6. 



Very compressed, with five excavated ambulacra ; apex central. 

 A cast from the Deep cut of the Chesapeake and Delaware Canal. 

 Diameter one inch. 



ECHINUS. 



E. infulatus. (S. G. M.) PI. X, fig. 7. 



Five pairs of tubercles running from mouth to apex, as they ap- 

 proach the latter converging and becoming smaller : intermediately 

 are four other rows of tubercles, commencing at the mouth and ter- 

 minating just above the margin. Diameter three fourths of an inch. 

 Calcareous strata of South Carolina. 



CLYPEASTER. 



. C. geometricus. (S. G. M.) PI. X, fig. 9. 

 Hemispherical ; ambulacra elevated, formed of two pairs of lines, 

 connected by transverse striae : mouth stelliform, with five radiating 

 ridges that cross the margin and meet the ambulacra. Delaware 

 and Chesapeake Canal. 



SCUTELLA. 



S. crusiuhides. (S. G. M.) PI. X, fig. 8. 



Sub-orbicular, thick, center elevated ; ambulacra five, short, ellip- 

 tical. Diameter three fourths of an inch. Obtained (together with 

 all the calcareous species of this supplement) by my friend, Mr. T. 

 A. Conrad, in the Southern states. 



Explanation of Plates IX and X. 



PLATE IX. 



Fig. 1. Baculites compressus. Fig. 3. Cardita decisa. 

 2. Teredo tibialis. 4. Gryphfea plicatella. 



