FAMILY PYRAMIDELLIDM. 



Shell turriculated, composed of nuraerous whorls, with long 

 spire, the apex heterostrophe ; aperture entire, the outer lip 

 generally sharp, the columella with one or several plications. 

 Operculum corneous, paucispiral, with excentric nucleus, the 

 columellar margin sinuated. 



Animal with flattened, ear-shaped tentacles channeled outside 

 towards their extremity, connate at the base; eyes sessile, 

 immersed at the icner sides of the base ; proboscis long, retrac- 

 tile, coming from an orifice situated immediately below the base 

 of the tentacles ; veil distinct, elongated, entire or divided in 

 front reaching to the anterior margin of the foot ; foot truncated 

 or sinused in front, extending far beyond the head, attenuated 

 behind. Probably carnivorous, but the lingual teeth are want- 

 ing, or rudimentary. 



No zoological characters of importance separate this family 

 from the Turbonillidse ; the distinction is mainly one of conve- 

 nience, the present group containing those shells, usually larger, 

 having two or more columellar plications (only one in Syrnola), 

 the Turbonillidse being composed of minute shells having a single 

 small plication, or without any. 



The heterostrophe and turned-over summit of the spire is one 

 of the most remarkable features of the shell, a character found 

 in few o'ther families of mollusks. In the animal the presence of 

 a mentum or veil is also a curious feature. It is developed below 

 the mouth, and may be derived from the conjunction of buccal 

 tentacles, or perhaps represents the propodium, as in Natica. 

 The genus Pyramidella and its subgroups contain all the living 

 species of the family, and a few fossils, cretaceous and tertiary ; 

 the other genera are exclusively fossil. " The Pyramidellidse 

 present subjects of much interest to the students of extinct 

 mollusca ; numerous forms, bearing all the aspect of being mem- 

 bers of this family occur. . . . Many of them are gigantic 

 compared with existing species, and the group, as a whole, may 



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