486 THE PALEONTOLOGY OF MINNESOTA. 
(Classification of paleozoic Lamellibranchiata. 
Family CYPRICARDINIID, (Provisional.) 
GENUS: Cypricardinia, Hall. 
Family CYRTODONTID A, Ulrich. 
GENERA: ? Cypricardites, Conrad; Cyrtodonta, Billings; Ischyrodonta, Ulrich; Matheria, Billings; Orlonella, 
Ulrich. ? Ptychodesma, Hall; Vanuxemia, billings; Whitella, Ulrich. 
Suborder HOMOMY ARIA. 
Mantle lobes either separate or united posteriorly. The two adductor muscles of nearly equal 
strength. 
Family ARCIDAS, Lamarck. 
GENERA: Carbonarca, Meek and Worthen; Macrodon, Lycett; Nyassa, Hall; ? Spenotus, Hall. 
Family PARARCIDA, (Provisional). 
GENERA: Cardiola, Broderip; Cardiopsis, Meek and Worthen; Dewiobia, Winchell; Glyptocardia, Hall; 
Lunulicardium, Minster; Orecardium, Herrick; Panenka, Barrande; Paracardium, Hall; 
Pararca, Hall. 
Family NUCULIDAS, Gray. 
GENERA: ? Clidophorus, Hall; Ctenodonta, Salter (Tellinomya, Hall ); Goniodon, Herrick; Nucula, Lam- 
arck; Nuculana, Link; Nuculites, Conrad; Palceoneilo, Hall; ? Pyrenomeeus, Hall; Yoldia, 
Moller. 
Family LYRODESMIDAS, Ulrich. 
GENERA: Adodesma, Ulrich;—Ischyrina,Billings;—Lyrodesma, Conrad; Lechnophorus, Miller> 
Bam, Seehnophortoar Wetlee 
Family TRIGONIDA4, Lamarck. 
GENERA: ? Cytherodon, Hall; ? Schizodus, King. 
Family UNIONID AS 
GENERA: ? Amnigenia, Hall; ? Anthracosia, King; Prisconaia, Conrad. 
Family ELYMELLIDA), (Provisional). 
GENERA: Elymella, Hall; Glossites, Hall. 
Order SIPHONIDA, Woodward. 
Mantle lobes more or less united; siphons of varying lengths, either separate or united, are 
developed; both adductor muscles well developed. 
Family SOLENOMYID/AS, Gray. 
GENERA: Solenomya, Lamarck; Clinopistha, Meek and Worthen; Phthonia, Hall. 
Family SANGUINOLITIDAS, Miller. 
IENERA: Promacrus, Meek; Sanguinolites, McCoy. 
