80 TURRITELLID.E. 



Genus TURRITEL'LA* Lamarck. PL II. f. 1 . 



Body cylindrical : mantle fringed at its edge : snout short, 

 contractile : tentacles separated by the snout : eyes placed on 

 slight prominences : opercular lobe entire. 



Shell pyramidal, spirally ridged or striated : spire having 

 the top whorls, when disused, partitioned off by a solid hemi- 

 spherical plug : mouth round, or inclining to square : operculum 

 rather solid, with numerous whorls, the outermost of which 

 overlap one another, or are imbricated, and all are finely 

 puckered in an oblique direction ; nucleus central. 



Old English naturalists called these shells " screws/ 5 

 Thev are not, like their human namesakes, confined 

 to the civilized part of the globe, but are met with 

 everywhere, in great variety. The species are numerous 

 and prolific, inhabiting the coralline and deep-sea zones. 



In a fossil state thev have been found in formations 

 certainly as far back as the Greensand. Our common 

 species is either very shy or very sluggish; it rarely 

 shows more than its foot and the tips of its tentacles. 

 I have been obliged to deprive it of the greater part of 

 its shell in order to examine the soft parts. The lingual 

 membrane is minute : each row of teeth consists of a 

 broad central plate or rhachis, flanked on either side 

 by three narrow and incurved pleurse. 



Turritella has several obsolete synonyms. 



Turritella te'rebra f, Linne. 



Turbo terebra, Linn. S. N. p. 1239. Turritella communis, F. & H. iii. 

 p. 172, pi. lxxxix. f. 1-3, and (animal) pi. II. f. 4. 



Body yellowish, mottled with brown and speckled with 

 white : mantle thick, fringed on its outer and inner edges with 

 fine filaments [arranged in a triple row, and reflected (Loven)]: 

 snout broad, depressed, bilobed towards the extremity, which 

 is delicately scalloped round the margin [tuberculated at the 



* A diminutive from furris, a tower. t A borer. 



