CONCHOLOGY. 133 
right edge having a thickened varix. Inhabits the Mediterranean 
and Northern Seas. Two species. 
Struthiolaria nodulosa. Struthiolaria crenulata. 
9. Genus Ranelia. Pl. XI. 
Animal. Unknown. 
Shell. Oval, and, as it were, depressed by the preservation of 
each side of a longitudinal thickened band ; aperture oval, almost 
symmetrical by the excavation of the columellar edge, terminating 
anteriorly by a short canal, often a little sloping; a ‘sinus at the 
posterior junction of the two edges. This genus forms a distinct 
division between the Murex and Struthiolaria. Inhabits the 
Northern and Mediterranean Seas. One species is found in 
America. Ffteen living species. Five fossil. 
Ranella gigantea. Ranella leucostoma. 
R. candisata. R. Argus. 
R. ranina. R. spinosa. 
R. bufonia. R. granulata. 
R. granifera. R. semigranosa. 
R. bitubercularis. R. crumena. 
R. anceps. R. pygmeza. 
R. caudata*. 
10. Genus Murex. Pl. XI. 
Animal, See Pleurotoma, above. 
Shell. Usually oval; the spire but slightly elevated, roughened 
with longitudinal, transversal bands or varices; aperture small, 
quite oval, and symmetrical by the excavation of the left edge, 
formed by a lamina applied upon the columella, terminated an- 
teriorly by a middling canal sometimes very long and closed ; the 
right edge more or less furnished with varices. Operculum horny, 
complete, oval, nearly circular, with sub-concentric partitions; 
summit terminal. This genus comprehends only such shells as 
have only three or more variceson each whorl. These varices 
show how often the animal has increased the size of its shell. 
Found in all seas. Seventy-three living species. ‘['wo fossil. 
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