FAMILY PURPURIDJE RANELLA. 139 



GENUS RANELLA. Lamarck. 



Animal unknown, but supposed to resemble that of Murex. Shell thick, oval-oblong, nodu- 

 lous, having a series of varices on each side, formed at each half revolution. Aperture 

 oval above, ending in a notch above and a straight canal beneath : lip thickened. Opercle 

 unknown. 



Ranella caudata. 



PLATE Vni. FIG. 176. a. b. 



(STATE COLLECTION.) 



Ranella caudata. Say, Jour. Acad. Nat. Sciences, Vol. 2, p. 236. 



R. id. Id. American Conchology, pi. 48, 



R. id. Adams, Bost. Jour. Nat. Hist. Vol. 2, p. 269. 



R. id. Gould, Invertebrata of Mass. p. 298, fig. 204. 



Description. Shell solid. Wliorls five, flattened above, cancellate, with eleven stout verti- 

 cal ribs, of which the one bordering the aperture, and one on the left side of the body-whorl, 

 are enlarged into stout knobs ; these are crossed by numerous revolving filiform hnes, which 

 form a reticulated surface. Lip thick, bordered within by raised granules. Columella curved, 

 flattened and smooth : canal narrow, deep and almost closed in front, as long as the spire. 



Color. Dark reddish brown ; internal margin of lip white or bluish white. 



Length, 1-0. Width, 0-5. 



This animal is common on our shores, and on those of the southern coast. It does not 

 appear to range north of Cape Cod. 



GENUS COLOMBELLA. Lamarck. 



Animal oflfering the family characteristics, but as yet incompletely known. Shell oval : spire 

 short ; base of the aperture more or less emarginate, and destitute of a canal ; columella 

 plaited ; lip thickened by an internal prominence, which narrows the aperture. Opercle 

 homy, elliptical. 



CoLOMBELLA AVARA. 



PLATE Vm. FIG. 179. 



(STATE COLLECTION.) 



Cohmbella avara. Say, Jour. Acad. Nat. Sciences, Vol. 2, p: 230. 



C. id. Adams, Jour, Nat. Hist. Vol. 2, p. 264. 



C. id. Gould, Invertebrata of Mass. p. 313, fig. 197. 



Description. Shell thick, small, elongate-ovate ; spire elevated and acute. Whorls six or 

 seven very slightly convex, almost flat : suture distinct. Surface with spiral impressed 



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