96 OF COXCHOLOGY. 



jS7/)wpsis of characters. 



TEREBRATULIDM.—Vnnci^ie, foraminated, pedunculate, 

 valves articulated. Bracliiferous, with non- 

 spiral apophyses. 

 TEREBRATULIN^E.— Hremal valve bearing a simple loop, 

 attached only to the hinge margin ; pro- 

 vided ■with crura. 

 Tereeratula. — Loop simple, crura separated. 



Terebratula. — Shell ovate. Brachia behind the mouth, 

 provided with two lateral and a median spiral 

 lobe. 

 CentroncUa. — Mesial sinuation of the loop prolonged 



neurally, as a thin lamina. 

 ? Epitliyris. — Hinge plate pointed, prolonged beneath 



the loop. 

 Pygope. — Shell bilobed when young ; lobes uniting and 

 leaving a central perforation, in the adult. 

 Rensseljeria. — Hinge plate perforate internally. Anterior 

 part of the loop pointed before, wider behind, 

 long, with a slender process neurally perpen- 

 dicular to the posterior edge. 

 Terebratulina. — Loop with the tips of the crura united 



forming a more or less sinuous ring. 

 Waldheimia. — Loop elongated and reflected, crura sepa- 

 rated. 

 Cryptonella. — Loop with a transverse band uniting the 



apophyses behind the crura. 

 Waldheimia — Ovate, inflated ; crura short, cardinal pro- 

 cess and border moderate. 

 3Ieganteris. — Orbicular, compressed, nearly equivalve. 

 Crura long, projecting over the edge of the re- 

 flected loop. Cardinal process and border, large. 

 STRINGOCEPHALINiE.— Cardinal process produced and 

 bifid. Loop not reflected, submarginal ; 

 attached to the crura by their neural 

 edges (?) ; both valves with a septum. 

 Stringocepiialus. — Loop provided with thin processes 

 converging internally. Neural septum fitting 

 into the bifurcation of the cardinal process. 

 Foramen very large, triangular, when young ; 

 round and small when adult. 

 MAGASIN^. — Loop reflected, attached both to the hinge- 

 line and to a haemal septum. 



