104 COLUIVIBELLA. 



the Cretaceous and Jiirassic colurahelloid shells belonging to 

 distinct genera. 



Section 1. Columbella (typical). 



Shell Strom] )ifonn, smooth, with short spire. 

 C. Strombiformis, Lam. Fl. 42, figs. 5-10. 



Shell stroml)iform, the body-whorl much swollen around the 

 upper part and somewhat produced at the posterior end of the 

 aperture ; cliestnut-color, witli the sinre and middle and lower 

 portion of the l)ody-whorl minutely' white-spotted ; sometimes 

 the spots coalesce into zigzag white markings ; there are also 

 usually a few irregular large white spots on the shoulder or 

 middle of the body-whorl ; interior usually white, sometimes 

 orange-tinted ; epidermis thick, shaggy, longitudinally striated, 

 frequently decussated posteriorly or throughout by revolving 

 strife ; operculum very variable in form, the initial point usually 

 terminal and basal but occasionally even subcentral, or marginal 

 at.the centre of its length. Length, •83-l'4 inches. 



West Coast of Central America to Mazatlan; Oulf of California. 



With this si)ecies is to be united G. major ^ Sowerby (figs. 6-8), 

 which Carpenter and others have suspected to be a A'ariet}', having 

 dots' instead of the zigzag white markings and the spiral sculpture 

 of the epidermis on the shoulder only, instead of all over ; neither 

 these, nor the other inferior distinctive characters given, hold 

 good when a large series of specimens is examined. Fig. 8 

 represents a smaller, but adult shell ; it is a minor race, which, 

 as in so many of the species of mollusks usually accompanies 

 the normal-sized individuals. Other synonyms are C. gibbosa, 

 Duclos (fig. 9), C. Bridgesi, Reeve (fig. 10), not full grown. 



C. Paytensis, Lesson. PI. 42, figs. 11-14. 



Whorls broadly channeled below the sutures: chestnut-brown, 

 minutely dotted with white throughout. Length, 1-1 -15 inches. 



Payta, Peru; Chili. 



This may possibly he a variety only, of the preceding species ; 

 the sutural channel is strongl}' marked, however, in the numerous 

 specimens before me. C. sjna-ca, Sowb., C. rudica, Sowb. 

 Genera of Shells (fig. 14), and C. Paytalida^ Duclos (fig. 13), are 

 synonyms. 



