LEUCONIA. 247 



high-water mark. West Columbia, Chili, and Peru are the 

 countries from which the species of Marinula are chiefly 

 procured. One, M. nigra, of Philippi, is from the small 

 Island of Tristan D'Acuna. The sub-genus Turcia is, 

 however, European in its geographical distribution, being 

 found in the Mediterranean ; it has also been detected in 

 Madeira. 



Species of Marinula. 



Callaonensis, Petit. pepita, King. 



cymbseformis, Recluz. xanthostoraa, H. and A. 

 nigra, Phil. Adams. 



patula, Lowe. 



Sub-gen. monica, H. and A. Adams. 



Shell oblong-conical ; spire elevated, whorls transversely 

 striated ; outer lip thickened internally, and furnished with three 

 plait-like teeth. 



;equalis, Lowe. gracilis, Lowe. 



Firminii, Payr. 



Genus LEUCONIA, Gray. 



Foot divided inferiorly by a transverse groove. 



Shell ovate-oblong, imperforate, smooth ; spire conical 

 aperture elongate, oval ; inner lip with two plaits anteriorly ; 

 outer lip smooth internally, the margin simple, acute. 



Ex. L. alba, Montagu, pi. 83, fig. 3. 



The British Islands and the North of Europe are the 

 abodes of these little Mollusks, which are amphibious in 

 their habits, living among the stones of sea-beaches between 

 tide-marks. 



