MONOGRAPH OF THE GENUS 



GALEOMMA, Turton. 



Genus. — Molluscum acephalum, bimusculosum ; testa bivalvi, 

 transversim ovata, terminibus subacutisomnino divaricatim striata, 

 striis dorsalibus divaricatim adscendentibus ; valvis ad marginem 

 ventralem late hiantibus ; cardine edentulo seu dentibus utraque 

 valva duobus parvis, quorum una nonnunquam duplicate ; liga- 

 mento parvo, lineari, interno ; pallii impressione integra. 



In distinguishing between the species of this genus and those of 

 Scintilla, I have thought the best guide would be the presence 

 of sculpture in the former and its absence in the latter, and have 

 therefore displaced the four species included by M. Deshayes in 

 bis division of Galeomma, described as " lisses et brillantes a 

 ouverture mediocre," namely, ambigua, splendida, polita, and Lay- 

 arcli. The Galeommse lie in mud and sand under stones, with 

 their valves spread open. 



In the following descriptions, I have chosen rather to attend to 

 comparative characters than to repeat those which are more posi- 

 tive. I adopt this method in concurrence with the following sen- 

 imcnts expressed by Button : — ■ 



"It is only by comparing that we can judge, and our know- 

 ledge turns entirely on the relation that things bear to those which 

 resemble them." 



Species of Galeomma. 



Plate 234. 



1. G. Turton-i (f. 1, 2, 3, 4), Sowb.— Test& oblonga, alba, ad 

 latera oblique subtruncata, terminis acutis, striis elevatis duplicates 

 et divaricatis moniliferis sculpta, striis ad marginem dorsalem ad- 

 scendentibus, margine ventrali valide hiante ; cardine edentulo. 

 06s. The pointed ends and wide hiatus of this white British shell 

 are well known. The sculpture consists of beaded strife diverging 

 in pairs and rising upwards towards the dorsal edge. 



vol. in. x 



