98 



TURBO. 



A. Pillar margin of the aperture dilated, imper- 



forate. (Plate XIX. Fig. 4.) 



B. Solid, imperforate. (Fig. 5.) 



C. Solid, perforate. (Fig. 6.) 



D. Cancellate. (Fig. 7.) 



E. Tapering. (Fig. 8.) 



Shell univalve, spiral. Aperture coarctate, 

 round, entire. 



The shells of the genera Turbo and Trochus 

 are extremely similar, and are much intermixed in 

 the Linnaean arrangement ; yet the round aperture 

 of the one, and the angular form which charac- 

 terizes the other, ought sufficiently to point out to 

 which each belongs. The probability is, however, 

 that the Turbines which have escaped from their 

 proper genus, are fewer than the strangers which 

 have been admitted into it. The rotundity of the 

 mouth is a less indeterminate diagnosis than that 

 of almost any other genus ; and even in these spe- 

 cies in which it has an inclination to oval or ovate, 



