Family PYRAMIDELLID^. 



Shell turriculated, composed of numerous 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 inner sides of the base ; proboscis long, retrac- 

 tile, coming from an orifice situated immediatelj' 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 Turbonillidae ; the distinction is mainly one of conve- 

 nience, the present group containing those shells, usuall}^ larger, 

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

 the Turbonillidae 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 other 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 P3-ramidella and its subgroups contain all the living 

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

 the other genera are exclusively fossil. " The Pyramidellidae 

 present subjects of much interest to the students of extinct 

 moUusca ; 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 



(294) 



