GENERA OF SHELLS. 91 



acute at summit. Aperture longitudinal, much 

 shorter than the spire, emarginate posteriorly 

 at base. Base of the columella twisted or ob- 

 lique. 



The very short columella of this shell presents a 

 peculiar character ; in its general form it much resem- 

 bles the turritella, but is distinguished by its aperture, 

 and by the notch at the posterior part of the base ; from 

 eburna by not having the channelled umbilicus, and 

 from buccinum by the small proportion which the 

 length of the aperture bears to the spire. 



T. maculata, flammea, crenulata, dimidiata, muscaria, 

 subulata, oculata, duplicata, Babylonia, corrugata, Senega- 

 lensis, coerulescens, striatula, chlorata, cerithina, raphanula, 

 cingulifera, myuros, scabrella, strigilata, lanceata, aciculina, 

 granulosa, vittata. 



COLUMELLARIA. 



JY*0 canal at the base of the aperture, but a more or less dis- 

 tinct subdorsal notch, and plaits on the columella. 



COLUMBELLA. Shell oval, spire short. Base 

 of aperture more or less emarginate ; no canal. 

 Columella plaited. Outer lip dilated inter- 

 nally, narrowing the aperture. 



The shells of this genus are short, small, and of con- 

 siderable thickness, often striated transversely and of 

 various colors. They are distinguished from volutaby 

 the swelling on the inside of the outer lip and by hav- 

 ing an operculum. 



C. strombiformis, rustica, mercatoria, flavida, semipunc- 

 tata, bizonalis,reticulata, hebraea, pardalina,scripta, ovulata, 



