1422 BULLETIN 92, UNITED STATES NATIONAL MUSEUM. 



Order OPISTHOBRANCHIA. 

 Suborder PTEROPODA. 



Family CAVOLINIED/E Fischer. 

 Coleoprion Sandberger, Styliola Lesueur. 



Family HYOLITHID^E Nicholson. 

 Hyolithes Eichwald, Matthevia Walcott, Pterotheca Salter. 



Suborder CONULARIIDA. 

 Family TENTACULITID^E Walcott. 

 Tentaculites Schlotheim. 



Family TORELLELLID^E Holm. 

 Coleolus Hall, Hyolithellus Billings, Salterella Billings. 



Family CONULARIIDA Walcott. 

 Conularia Miller, JSphenothallus Hall. 



Class CEPHALOPODA. 

 Subclass TETRABRANCHIATA. 



Order NAUTILOIDEA. 



Family ENDOCERATID/E Hyatt. 



Cameroceras Conrad, Cyclendoceras Grabau and Shinier, Endoceras Hall, Narthe- 

 coceras Hyatt, Nanno Clarke, Suecoceras Holm, Vaginoceras Hyatt. 



Family PILOCERATID.E Hyatt. 

 Clarkoceras Ruedemann,? Cyrtocerina Billings, Piloceras Salter. 



Family CYRTENDOCERATID^ Hyatt. 

 Cyrtendoceraa Remele. 



Family ASCOCERATID^E Barrande. 

 Ascoceraa Barrande, Glossoceras Barrande. 



Family MESOCERATID;E Hyatt. 

 Billingsites Hyatt. 



Family ORTHOCERATID^E McCoy. 



Baltoceras Holm, Geisonoceras Hyatt, Orthoceras Breynius. 

 Family CYCLOCERATID/E Hyatt. 



Cycloceras McCoy, Dawsonoceras Hyatt, Orygoceras Ruedemann, Protocycloceras 

 Hyatt, Spyroceras Hyatt, Kionoceras Hyatt, Protokionoceraa Grabau and Shimer. 



Family TARPHYCERATID^ Hyatt. 



Aphetoceras Hyatt, Barrandeoceras Hyatt, Deltoceras Hyatt, Eurystomites Schroder, 

 Tarphyceras Hyatt. 



Family TROCHOLITID^E Hyatt. 



Apsidoceras Hyatt, Discoceras Barrande, Gyroceras Dekoninck, Litoceras Hyatt, 

 Mitroceras Hyatt, Pycnoceras Hyatt, Schroederoceras Hyatt, Trochoceras Barrande, 

 Trocholites Conrad, Trocholitoceras Hyatt. 



