78 CLASS I. TROPIOPODA. ORDER I. BIMUSCULOSA. 



GALEOMMA, Turton. 



Testa tenuis, parva, oblongo-ovata, requivalvis, aequilateralis, margine 

 ventrali hians. Dens cardinalis in utraque valva unicus, ligamento 

 parvo, duplici, partim interno, partim externo. Impressio muscu- 

 laris pallii inter rupta, sinu nullo. 



The genus Galeomma was introduced by Dr. Turton, and characterized 

 from some specimens found on our own coast. It also includes a species 

 from the Mauritius, described by Lamarck as a Psammobia, though differ- 

 ing materially from his other Psammobia both in size and general aspect. 

 The animal, which has been carefully examined by Gray, is said to agree 

 in some particulars with that of Gastrochcena ; he does not, however, 

 express any opinion as to the situation it should occupy in the general 

 classification, and therefore leaves us in doubt as to the propriety of re- 

 taining it with the Nymphacea. 



The shell of Galeomma is described as being thin, small, oblongo- 

 ovate, equivalve, equilateral, and gaping at the ventral margin. There 

 is one cardinal tooth in each valve, and the ligament is small and duplex, 

 partly internal and partly external. 



The muscular impression of the mantle is interrupted, but without 

 exhibiting any sinus. 



Examples. 



PI. L1V. Fig. 1 to 3. 



Galeomma Turtoni, Sowerby, Zool. Journal, p. 361. pi. 13. f. 1. Ge- 

 nera of Shells, No. 37. 



PL LIV. Fig. 4 and 5. 



Galeomma Mauritiana, Sowerby, Genera of Shells, No. 37. 

 Psammobia aurantia, Lamarck. 

 Galeomma aurantia, Deshaves. 



