CHAP. VII. MELAMPUS. — SCISSURELLA. 209 



branchia also pectiniform, we have no means of knowing. 

 The aspect of their shells, however, induces me to place 

 them for the present in the same group, more especially 

 since we have already shown they would altogether dis- 

 turb what we think is the natural series of Auricula and 

 Clausilia. We do not attach any importance to the fact 

 of Geovula having an epidermis, because, although the 

 excellent zoologist just named thought otherwise, we 

 possess several specimens of a typical West Indian Me- 

 lampus, where a thin brown epidermis is over the whole 

 shell ; and this also is common to the sub-genus Rhodo- 

 stoma. The peculiar depression of the numerous whorls 

 of the spire in Geovula, Scarahus, Melampus, and Rho- 

 dostoma, strikingly contrasts again with the few and 

 produced volutions of the true Auriculce ; and the whole 

 are separated from Tornatella, by the animal of the latter 

 having an operculum, and being differently formed. Tor- 

 natella, in fact, seems to represent the sub-genus 3fe- 

 lampus ; while Truncatella of Lowe, probably^ does the 

 same in the circle of Turritella. The whole of this 

 sub-family, however, requires much more attention than 

 we have yet been able to give it. 



(193.) We place the genus Scissurella as the only 

 type of our last division, from a belief that it is analogous 

 to lanthina. It was first characterised by M. D'Orbigny, 

 one of the most eminent naturalists of France, who found 

 his specimens among sea sand. It is very minute, and 

 the animal is unknown : its general shape is that of Si- 

 gnretus or Vitrina, but there is the same sort of long 

 narrow slit in the outer lip as is seen in the Pleuroto- 

 mince, m Plevrotoivaria, and m lanthina; thus we have 

 numerous analogies, while in affinity we consider this 

 genus to be the patelliform type of the TurhincE. The 

 very beautiful figures in Mr. Sowerby's Genera, is all 

 we yet know of Scissurella; but we possess two or three 

 similar shaped shells, which appear closely connected to 

 this type, and probably enter into the same genus. 



(194.) We shall now take a rapid view of the five 

 genera which appear to compose the sub-family before us. 



p 



