110 SYSTEMATIC ARRANGEMENT 



" Subtentaculo Turritellce triplicate dextro lobus oblongus, lobus 

 lateralem Trochorum referens, alter lobus similis magis postice et in- 

 ferius situs est. In cervice lobus transversus conspicitur margine 

 crispato. Pallii margo fimbriatus, lobis latis incisis ; in pagina interna 

 cirri brevissimi tres adsunt. Affinitas magna cum Cerithiis in propa- 

 tulo est." — Phil. Sicil. ii. 160. Very different from the descriptions 

 of the animal of Turritella terebra, Philippi, Moll. Sicil. i. 191. 



Fig. 57. — Teeth of Turritella ungulina. 



Central tooth of Turritella ungulina subquadrate, wider at the 

 base, cutting edge triangular, denticulated ; first lateral tooth with 

 the tip recurved, serrulated on both sides ; second and third similar, 

 angularly hooked, strap-shaped, serrulated on both sides (fig. 57). 



The animal of Turritella alternata, like Melania virginica, and in 

 common with many freshwater shells, has the power of gliding along 

 the surface of the sea with the shell downwards. The rostrum about 

 one-third the length of the tentacula. Tentacles filiform, cylindrical, 

 obtuse at the tip, nearly as long as the foot, white, brown ringed. 

 Eyes not prominent, at the outer base of the teutacles. Foot longer 

 than the aperture of the shell, rather acute behind, truncate a little 

 convexly in front. The shell when taken from the water becomes 

 cinereous white. Operculum horny, blackish. — Say. 



2. Zaria. 



Shell turrited, spirally ribbed ; mouth ovate, subquadrate ; outer 

 lip simple. 



1. Z. duplicata. Turritella d., Kiener, t. 128. f. 7; Adams, Gen. 

 Moll. t. 38. f. 3. 



3. Torcula. 



Shell turrited ; whorls subangular in front, with a deep sunken 

 central groove ; mouth subquadrate ; outer lip with a deep roundish 

 central sinus. Operculum ? Animal ? 



1. T. exoleta, Adams, Gen. Moll. t. 38. f. 2 (shell only). 



§§ Mouth nearly circular, simple in front. 



4. Eglisia. 



Shell turrited, spirally ribbed ; whorls rounded, with a deep 

 sutural groove ; mouth roundish ; outer lip simple. 



1. E. spirata, Adams, Gen. Moll. t. 38. f. 5 (shell only). 



