414 paphiiNjE. 



fresh state, covered with a thick, greenish-brown epidermis, 

 and are transversely ovate. They inhabit the sands of 

 estuaries in New Zealand and other parts of the world. 



Species of Mesodesma. 



erycinea, Lam. Novas Zelandice, Chem. 



mactroides, Desk. ovalis, Desk. 



Genus CERONIA, Gray. 



Shell ovate-cuneate, truncated behind. Hinge with the 

 lateral teeth sub-equal, compressed, strongly cross-grooved. 

 Siphonal inflection distinct. 



Ex. C. Jouresii, Joannis, pi. 106, fig. 3, 3, a. 



The species of Ceronia, at present discovered, are rugose 

 and covered with an epidermis ; the lateral teeth are 

 curiously grooved. They are from California. 



Species of Ceronia. 



arctata, Conr. Jouresii, Joannis. 



donacia, Lam. lanceolata, Desh. 



Genus DONACiLLA, Lamarck. 



Shell elongate, wedge-shaped, hinder slope truncated. 

 Hinge with the anterior lateral teeth elongate, the hinder 

 short. Siphonal inflection distinct. 



Syn. Donacina, Blainv. 



Ex. D. cornea, Poll, pi. 100, fig. 4. Shell, D. cornea, 

 fig. 4, a, 4, h. 



