CONCHOLOGY. 145 



9. Ranella. Fourteen species. 



This gerius of shells has two rows of varices or thickened 

 tsands, arranged on either side in rows, so that it forms a 

 distinct division between the Struthiolaria and the Murex. 



Shell oval, as if depressed by the preservation of each 

 side of a longitudinal thickened band ; aperture oval, almost 

 symmetrical by the excavation of the columellar edge, ter- 

 minating anteriorly by a short canal, often a little sloping ; 

 a sinus at the posterior junction of the two edges, 



Ranella gigantea. Ranella granulata^ 



R. leucostoma. R. granifera. 



R. candisata. R. semigranosa. 



R. Argus. R. bitubercularis. 



R. ranina. R. crumena. 



R. spinosa. R. anceps. 



R. bufonia. R, pygmsea. 



R. ranina. The froglike Ranella. PI. 25, fig. 2. 

 Species not umbiUcated. 



R. granulata. The granulated Ranella. 

 Species not umbilicated. 



R. spinosa. The prickly Ranella. 



Species of which the varices have elongated spines ; beak 

 sulcated ; outer lip internally crenated ; acute, short, distinct 

 muricated tubercles ; fawn coloured. 



10. MureX. The Trumpet Shell. Sixty-six species. 



Though so greatly divided by Lamarck, this is a beauti- 

 ful and numerous genus, comprehending only such shells as 

 have three or more varices on each whorl. 



These varices show the number of times the animal has 

 increased the size of its shell, and what proportion is added 

 at each increase. 



The shells are generally irregular in form, arising from 

 their surfaces being usually armed with spines, knobs, stria, 

 or foliations. 



T 



