UNIVALVES. 



PLATE XXXII. 



Genus. PLEUROTOMA. 



Character. Shell spiral, spindle-shaped, acuminate; the spire and beak long; 

 the cheek of the mouth projecting, and hollowed out with a circular opening or 

 trench, as if cut out with a knife, 



Species. 



No. 1. Pleurotoma contorta. Shell brown, streaked with twisted lines of red ; 

 the spire strongly tuberculated, acuminate, and doubly ridged ; the opening 

 in the cheek large and obvious ; the beak much twisted ; the spire elegantly 

 tapering. Native place not at present ascertained. From a shell in the Col- 

 lection of Mr. Bullock. 



No. 2. Pleurotoma lineata. Shell pale red, streaked across with red veins ; the 

 spire rotund and slightly canulated ; beak long and open. From a shell in 

 the Author's Museum, supposed to have been brought from the southern 

 latitudes. 



No. 3. Pleurotoma zebra. Shell white, richly streaked across with interrupted 

 dark stripes, from whence its name ; the general form of the body and spire 

 very angular, and the whole character curious and strongly marked. From 

 a shell in the British Museum. 



No. 4. Pleurotoma albida. Shell white, and beautiful, formed into angular 

 ridges to the top of the spire, and slightly shaded with red ; there is an ex- 

 quisite delicacy in the shape of the whole shell, which is nevertheless very 

 thick and strong. From a specimen in the Author's Museum, and, like all 

 its other congeners, from the South Seas, being frequently found at New 

 Zealand and Lord Howe's Island. 



No. 5. Pleurotoma babylonica. Shell spiral, turreted ; the spire divided into 

 different stages or heights, giving a faint idea of the tower of Babel, from 

 which circumstance it takes its name. It is a common shell, and had for- 

 merly been improperly placed by Linnseus under the genus Murex. 



REMARKS. 



The genus Pleurotoma is distinguished from all other shells by the slit or opening in the side 

 of the mouth, also for its general resemblance to a spindle, by which latter name these shells 

 have sometimes been called. They are not numerous in the recent state, and are found only 

 in the southern regions of the globe : nevertheless, immense quantities and varieties of them 

 have been discovered in a fossil state in various parts of Europe. The genus Pleurotoma has 

 a faint and distant resemblance to the Rostellaria and Cerithium genera, before described, but 

 differs in the situation of the opening, which is the maxilla oris or cheek, and which is an in- 

 variable mark of the family. The amazing variety of the forms of Nature is in no division 

 more strongly evidenced than in the above shells. 



