430 SYSTEMATIC PALEONTOLOGY 



VERMES. 



Class ANNELIDA. 



Subclass CH/ETOPODA. 



Order POLYCH/ETA. 

 Suborder TUBICOLA. 



Genus SPIRORBIS Daudin. 



Spirorbis calvertensis n. sp. 

 Plate CXVIII, Fig. 18. 



Description. — Tubes small, thin, spirally coiled, attached by flat under 

 side to mollusean shells ; surface with indistinct somewhat irregular an- 

 nulations which are most distinct on the tops of the younger coils ; coils 

 somewhat sharply ridged on top. 



Diameter of coils, 1.3 mm. ; diameter of tube, .4 mm. 



Occurrence. — Calvert Formation. Plum Point. 



Collections. — Maryland Geological Survey, U. S. National Museum. 



• ECHINODERMATA. 



Class ECHINOIDEA. 



Order SPATANGOIDEA. 



Family SPATANGIDyE. 



Genus ECHINOCARDIUM Gray. 



Echinocardium orthonotu:m Conrad. 



Plate CXIX, Figs, la, lb, Ic. 



Spatangus Orthonotus Conrad, 184.3, Proc. Acad. Nat. Sci. Phila., voL i, p. 337. 

 Amphidetus virginianus Forbes, 184.5, Quart. Jour. GeoL Soc. London, voL i, pp. 



425, 426, 3 figures. 

 Amphidetus virginianus Forbes, 1846, Proc. GeoL Soc. London, voL vi, pp. .5.59, .560, 



3 figures. 



