CLASS I 



PELECYPODA 



439 



Grammysia Vern. (Sphenomya Hall) (Fig. 650). Shell elongate-ovate, concen- 

 trically sculptured, with a deei^ lunule ; cardinal margin thickened, edentulous ; 

 surface with several radial 

 grooves. Silurian and De- 

 vonian. Protomya Hall is 

 similar but without the AmXil/i£K^i\\\lll]\ Xfl/I'i'J' '■ 



Leptodormis M'Coy, Sil- 

 urian ; Elymella, Glossites, 

 Euthydesma, Paleanafina 



and (?) Tellinopsis Hall ; 

 Devonian. 



Gardiomorpha Koninck, 



Fig. 650. 



n,^Ql i,^flof,irI K^oVc oi„.^c<- Grammysia hamiltcnensis Vern. Spirifer Sandstone (Lower Devonian) ; 

 uvai, mnaiea, oeakS almost Lahnstein, Nassau (after Santlberger). 



anterior, consj^icuous, ad- 

 jacent, jjrosogyrous ; hinge line thin, arched. Silurian and Carboniferous. 



Isoculia M'Coy. Like the preceding, but with coarse concentric sculpture. 

 Carboniferous. 



Other Carboniferous genera are Broeckia Koninck ; Ghaenomya Meek ; Sedgwickia 

 M'Coy ; and Edmondia Koninck. The last is like Gardiomorpha but gapes in front, 

 with a narrow ridge below the beaks. 



The Cambrian Fordilla Barrande, earliest of bivalves if a Mollusc, very likely belongs 

 to the bivalved Crustaceans near Estheria. It is minute, oval, somewhat arcuate, and con- 

 centrically striated. Lo^Ver Cambrian ; New York and Massachusetts. 



Another bivalved shell, regarded by some authors as a Pelecypod, Modioloides priscus 

 Walcott, from the Lower Cambrian of eastern New York, is probably also of Crustacean 

 affinities. Pizzaroa, Timaria and Bistramia Hoek, from' the Silurian of Bolivia, are probably 

 byssal bivalves. 



Family 5. Cardiolidae Neumayr. 



Shell equivalve, inflated, obliquely ovate, with prominent beaks, and edentulous hinge ; 

 sculpture often radial, or sometimes of concentric ridges which may be confined to the 

 beaks. Silurian and Devonian. 



Gardiola Bred. (Fig. 651); Gloria Barrande; Eopteria 

 (? Euchasma) Billings ; from the Ordovician, may also belong here. 



Family 6. Antipleuridae Neumayr. 



Shell very inequivalve without gape below the beaks; hinge 

 obscurely taxodont, with an amphidetic area and predominantly 

 radial sculpture. Silurian. 



Antipleura, Dualina and Dalila of Barrande. 



Family 7. Praecardiidae Neumayr. 



Shell equivalve with taxodont dentition and usually strong 

 radial sculpture. Silurian and Devonian. 



This family contains the following genera of Barrande from the Silurian of 

 Bohemia : Praecardium, Paracardium, Puella, Pentata, Buchiola {Glyptocardia Hall), 

 Praelucina, Regina, Praelima ; to which Neumayr adds Pleurodonta Conrath, and 

 Pararca Hall. It is possiljle that Silurina Barrande, regarded by Neumayr as the 

 type of a distinct family, may also be included. It is distinguished by its feelder 

 structure and a dorsal radial groove near the cardinal border. 



Fio. 651. 



Canliola mrnucopiac 

 Goldf. Devonian ; Ebers- 

 reuth, Piclitelgebirge. ^/j. 



