*^6 THE PALEONTOLOGY OF MINNESOTA. 



[Classifloation of paleozoic LamelUbranchiata. 



Family CYPRICARDINIID^, (Provisional.) 



Gestus : Uyprieardinia, HaM. 



Family CYRTODONTIDiB, Ulrich. 



Genera : ? Cypricardites, Conrad; Gyrtodonta, Billings; Ischyrodonta, Ulrich; Matheria, Billings; OHonella, 

 Ulricli. ? Ptyclwdesma, Hall; FariMxemia, Billings; Whitella, JJlvich. 



Suborder HOMOMTARIA. 



Mantle lobes either separate or united posteriorly. The two adductor muscles of nearly equal 

 strength. 



Family ARCID^, Lamarck. 



Genera: Carbonarca, Meek and Worthen; Macrodon, Lycett; Nyassa, Hall; ? Spenotus, Hall. 



Family PARARCID^, (Provisional). 



Genera: Cardiola, Broderip; Cardiopsis, Meek and Worthen; Uexiobia, Winchell; Olyptocardia. Hall; 

 Lunulicardium, Munster; OrcBcardium, Herrrck; Panenka, Barrande; Paracardium, Hall; 

 Par area. Hall. 



Family NUOULID^, Gray. 



Genera : ? Clidophorus, Hall; Ctenodonta, Salter (TeUinomya, Hall ); Ooniodon, Herrick; Nucula, Lam- 

 arck; iVMCMtana, Link; NucuHtes, Conrad; Palceoneilo, Hall; 1 Pyrenomceus, Hall; Yoldia, 



Moller. 



Family LYRODESMID^, Ulrich. 

 Genera: Allodesma, Ulrich; Ischyrina, Billings; Zyrodesma, Conrad; Technophorus, Miller. 



Family TRIGONIDiE, Lamarck. 

 Genera: ? Cytherodon, Ha,ll; ? Schizodus, King. 



Family UNIONIDiB 

 Genera: ? Amnigenia,TJ.a,\\; ? Anthracosia, King; Prisconaia, Conrad. 



Family ELYMELLIDiE, (Provisional). 



Genera : Elymella, Hall; Olossites, 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 SOLENOMYIDtE, Gray. 



Genera : SoUnomya, Lamarck; Clinopistha, Meek and Worthen; Phthonia, Hall. 



Family SANGUINOLITID^, Miller. 



Genera: Promacrus, Meek; Sanguinolites, McCoy. 



