200 



Melania semicarinatAj nob. Disseminator of Useful Know- 

 ledge, vol. 3. PI. 47, f. 4. 



Melania laqueata, nob. Disseminator of Useful Knov- 

 ledge, vol. 3. PI. 47, f. 1. 



Ranella. — Shell oval or oblong, more or less depressed in con- 

 sequence of having a range of varices only on each side, forming 

 a somewhat oblique longitudinal series ; aperture oval, the labium 

 being much arquated ; base canaliculated, sometimes a little emar- 

 ginated ; a sinus at the superior termination of the labrum ; epider- 

 mis distinct ; operculum horny ? 



Obs. These are the Frog and Toad shells of collectors, a genus 

 of well marked Marine shells dismembered by Lamarck from the 

 Linnean Murex, in consequence of their lateral margined character. 

 Montfort made another division of these shells ; to those with an 

 umbilicated columella he gave the generic name of Apollon, and 

 those which have no appearance of umbilicus he named Biiffo ; 

 these designations, or rather their corresponding words Appole and 

 Crapaud, are adopted by Blainville as subgenera of Ranella. 

 These shells are sufl&ciently distinct from those of any other group 

 and cannot be mistaken, if we except a few species which approach 

 Triton, (a name which ought to be changed, as it had been pre- 

 viously applied as a scientific designation by Laurenti to a genus 

 oi Amj)hibia) a genus which is distinguished by having its varices 

 rare and not at the equal distances of half volutions from each 

 other. The animal does not seem to be known, but judging by 

 analogy, it probably resembles that of Triton and Murex and ha? 

 therefore a horny operculum, composed of lamelliform elements, 

 disposed in an imbricated manner, and commencing at the superior 

 tip. It must also be carnivorous. 



Ranella caudata, nob. Jour. Acad. Nat. Sc. vol. , p. 236. 



Obs. This is a common species on the coast of the United 

 States. Its generic affinity is not always obvious, as in some 

 specimens the varix of the aperture, only, is well formed. PI. 48. 



Ceritiiium. — Shell more or less turritcd, often tubercular; aper- 

 ture small, oblique, with a short, truncated or recurved canal at 

 base which is not emarginated ; labium concave, more or less dis- 

 tinct, groove at the junction of the labrum with the preceding- 

 whorl J operculum small rounded. 



Animal much elongated ; mantle prolonged in a canal on the left 



