CONCIIIFEBA OR BIVALVES. 



81 



bosses prominent, thin epidermis. Animal un- 

 known. — 18 species recent. 



This genus presents a good deal of beauty, 

 the shells being often ornamented with lively 

 colours. There are species from the Indian 

 Ocean, North Sea, New Holland, &c. 



Here follows in Lamarck's system a genus 

 called Psammotcea, which is now discarded : it 

 seems to have been formed on imperfect shells. 



37. Galeomma (Turton). — Shell thin, 

 equivalve, inequilateral, gaping, 



one cardinal tooth in each valve; v 



the ligament is small and du- 

 plex, partly internal and partly 

 external. Animal unknown. — 2 species. 



Found in the Atlantic Ocean. A small 

 white and thin shell, covered with waved longi- 

 tudinal stripes. 



38. Tellina. — Shell nearly equivalve, trans- 

 verse or orbicular, and greatly compressed ; 

 the valves on the ligamental side irregularly 

 undulated ; cardinal and lateral teeth two, the 

 latter sometimes wanting ; ligament on the 

 shortest side. Animal, foot compressed and 

 pointed. — 62 species recent, and 16 fossil. 



G 



