MANUAL OF THE MOLLUSCA. 



IsoDOMA, Deshayes, 1860. 



Type, I. cyrenoides, Deshayes. Eocene. Paris basin. 

 Shell transversely oval, very thin ; hinge similar to that of 

 Cyrena, but the pallial line is sinuous. 



Family XVI. — Telliotd^.* 

 SowERBYA, D'Orbigny, 1850 (see p. 478). 



Dedicated to Sowerby, author of " British Mineral Con- 

 chology," &c. 



Type, S. crassa, D'Orb., Prodrome I., p. 362. 



Synonym, Isodonta, Buvignier, 1851. 



Shell equivalve, subequilateral ; right valve with two oblique, 

 diverging, cardinal teeth separated by a mesial trigonal socket, 

 and two lamellar lateral teeth separated from the hinge border 

 by longitudinal grooves ; left valve with a conical tooth between 

 two oblique pits ; laterals two ; longitudinal lamellar and pro- 

 jecting, and united to the superior border; ligament external. 



Fossil, 8 species. Lower Lias — Portlandian. England, 

 Prance, Germany. 



QuENSTEDTLA., Morris and Lycett, 1853 (see p. 481). 



Dedicated to Professor Quenstedt, the veteran palaeontologist 

 of "Wurtemberg. 



Type, Pullastra oblita, Phillips. 



Shell like that of Psammohia ; hinge with an obtuse transverse 

 cardinal tooth in the left, and a cardinal pit in the right ; liga- 

 ment external, in a narrow elongated groove ; posterior adductor 

 scar rounded, anterior elongated, sinuated ; pallial sinus smaller 

 than in Psammohia or Sanguinolaria. 



Fossil, 3 species. Liferior Oolite — Great Oolite. England, 

 France, Germany. 



? Pal^omya, Zittel, 1861. 



Shell triangular, depressed, nearly equivalve, inequilateral ; 

 right valve with two cardinal teeth, the i^osterior larger and in 

 front of the cartilage pit ; left valve with a single cardinal 

 tooth ; a prominent posterior lateral tooth in each valve ; 

 muscular and pallial impressions very faint. 



Fossil, 1 species. Coral Eag. Glos, Normandy. 



* See p. 479. 



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