MONOGRAPH OF THE GENUS 



SCINTILLA. 



Genus. — Molluscum acephalum, bimusculosuixi ; testa bivalvi, 

 polita, transversim subovata ; terminis rotundis seu subtruncatis ; 

 margine ventrali clauso vel paululum hiante, margitie dorsali non- 

 nunquam hiante ; cardine dentibus utraque valva duobus, quorum 

 postico nonnunquam duplicato, ligamento parvo, lineari, iuterno ; 

 pallii impressione integra. Obs. Very few of the species gape in 

 front, and none so widely as in the true Galeomma. Some of 

 them are open at the ends and dorsal margin. When living, the 

 valves lie spread open, with the mantle turned back over the edges 

 and often a great part of the surface, which probably gives them 

 the brilliant polish by which they are distinguished from Galeomma. 



Species of Scintilla. 



Plates 234, 235. 



Sect. I. Species with an hiatus in the ventral margin. 



1. Sc. Layardi (f. 20), Desh. — Testa tenuissima, alba, com- 

 pressa, suboequilatera ; terminis subtruncatis ; margine ventrali 

 hiante. Obs. It is like a true Galeomma, excepting that it has no 

 sculpture. 



2. Sc. sflendida (f. 14, 15). — Testa politissima, quam So. 

 Layardi altiore ; latere antico subtruncato. Obs. Much wider from 

 apex to base than Sc. Layardi, which otherwise it resembles. 



3. Sc. polita (f. 19), Desh. — Testa alba, compressa, tenui, 

 oblonga, subquadrata, concentrice undnlata; latere antico breviore, 

 truncato. Obs. A rather flat, thin white shell, truncated at both 

 extremities, slightly open in front. 



