LUCINA. 45 



ed the confidence of naturalists in their value. Clausinar 

 of Jeffreys can scarcely claim separation from the section 

 Cryptodon, though the minute shell for which it was found- 

 ed presents striking resemblances to a Kellia. Lucina 

 divaricata forms part of the genus Strigilla of Turton, and 

 marks a section curious for the wavy lines sculpturing the 

 surface of the shells it includes. Lastly, the pseudo- 

 British L. tigrina, with its allies, constitute an assemblage 

 equally remarkable for singularities of sculpture, but not 

 the less presenting the essential and peculiar characters of 

 Lucina. The name Codahia of Scopoli applies to this 

 subdivision. 



Lucince are distributed all over the world, and between 

 thirty and forty existing species have been described. 

 Nearly 150 fossil species are recorded from various forma- 

 tions, and they distinctly commenced their appearance 

 early in the secondary epoch, and probably sooner. The 

 elongated muscular scar is an excellent guide in determining 

 casts of fossil Lucina, though itself by no means so constant 

 in character throughout the genus as we could wish it to 

 be. 



* The characters of his genus Clausina, as given by Mr. Jeffreys himself in 

 the twentieth volume of the Annals of Natural History (July 1847) are as 

 follows : — " Testa pygmaea, orbicularis aut longitudinaliter rotundato-ovata, glo- 

 bosa, subajquilateralis, aaquivalvis, utrinque clausa, plerumque tegumine ferruginoso 

 vestita. Cardo in utraque valvula tuberculo et lamella laterali munitus. Apices 

 subcentrales ; lunula nulla ; ligamentum externum. Impressiones musculares ut 

 in Gyprina. n Mr. Gray has strangely placed it among his Tellinidm. 



