CHAP. VII. GENERA OF THE TURBINE. 20? 



here chiefly confine our notices to the five leading genera : 

 these appear to be Scalaria Lam., Turritella Lam., Turbo 

 Humph., Melampus Mont., and Scissurella D'Orbigny. 

 (190.) The genus Scalaria, as the circular-mouthed 

 group, represents Cyclostoma : the typical form seen in 

 the common wentletrap (S. pretiosa Lam.) has no pillar, 

 although it is a long spiral shell. These lead obviously to 

 Turritella,vf]\ere the shell is even more attenuated, so that 

 the whorls are fully as numerous as in Tercbra, which it thus 

 represents. Turbo (pukhra, fig. 3 t Q.) is the next genus, 

 differing chiefly, as regards the shell, 

 30 xJlb\ * n tne mner lip being broad and flat- 



tened, and the spire often very short, 

 or not longer than the aperture. 

 There is certainly a resemblance be- 

 tween many of these shells and the 

 more globose Trochidce, particularly 

 the sub-genera Pagodella and Echi- 

 nella, which are not perlaceous ; but 

 the great thickness and depression 

 of the pillar in Turbo, its perfectly round aperture, and 

 the convexity of the body-whorl, are sure marks of dis- 

 tinction. In the invaluable plates of M. Quoy, there is 

 a figure of the animal of a species of Turbo (under the 

 name of Littorina), which shows it to have almost a 

 zoophagous structure, so totally different indeed from 

 that of Trochus, that they have even no analogy to each 

 other. The same may be said of Phasianella, which is 

 only a long-spired Trochus, analogous, indeed, to Tur- 

 ritella, but with the short mouth and lateral filaments of 

 the Trochidce. 



(191.) The next genus, Melampus Montf., is one of 

 particular interest. It was originally proposed by Lamarck ; 

 but upon being told that they were land shells, he aban- 

 doned his name ofConovulus, and incorporated the species 

 in his genus Auricula. This was clearly a retrograde 

 movement ; for, even had his information been correct, the 

 difference of these two genera on one hand, and the close 

 resemblance between Tornatella and Melampus, is too ob- 



