FAMILY PERISTOMATA. 



189 



2. Bythinia tentaculata. Tentacled BytJiinia. 



Shell; conically ovate, with, a minute nearly closed umbilicus, 



fulvous green, subtransparent, apex 



rather sharp, whorls five, smooth, 



convex, the last rather ventricose ; 



aperture somewhat pyriformly ovate, 



lip dark- edged, scarcely reflected. 



Operculum subtestaceous, striated 



concentrically around a central 



nucleus. 

 Helix tentaculata, Linnaeus (1758), Syst. 



Nat. ed. 10. p. 774 

 Nerita jaculator, Muller (1774), Verm. Hist. 



part ii. p. 185. 

 Turbo nucleus, Da Costa (1778), Brit. Conch, p. 91. pi. v. f. 12. 

 Bulimus tentaculatus, Poiret (1801), Coq. de I'Aisne, p. 61. 

 Cyclostoma impurum, Draparnaud (1801), Tail. Moll. p. 41. 

 Turbo janitor, Yallot (1801), Hxere. d'Hist. Nat. p. 6. 

 Cyclostoma jaculator, Ferussac (1807), JEss. Meth. Conch, p. 66. 

 Lymncea tentaculata, Fleming (1814), Edin. Hncyc. vol. vii. p. 78. 

 Paludina impura, Brard (1815), Coq. Paris, p. 183. pi. vii. f. 2. 

 Paludina jaculator, Studer (1820), Kurz. Verz. p. 91. 

 Turbo tentaculatus, Sheppard (1823), Trans. Linn. Soc. vol. xiv. p. 152. 

 Bithynia jaculator, Eisso (1826), Hist. Nat. JEurop. Merid. vol. iv. p. 100. 

 Paludina tentaculata, Fleming (1828), Brit. Anim. p. 315. 

 Bithinia tentaculata, Gray (1840), Turt. Man. p. 93. pi. x. f. 120. 

 Bithinia (Hlona) tentaculata, Moquin-Tandon (1855), Hist. Moll. vol. ii. 



p. 528. pi. xxxix. f. 23 to 44. 

 Hab. Throughout Europe. (In gentle streams and still waters.) 



Bythinia tentaculata, the largest and most generally diffused of 

 our British species, is well distinguished by its filiform, irregularly 

 spreading tentacles. It was not improbably this peculiarity of 

 structure that suggested to the mind of Linnaeus the specific name 

 tentaculata. It will be seen also on reference to our vignette, that 

 they have a very flexible appearance, with sessile eyes at the base, 

 all of which characters go to show their distinctness from Paludina, 

 and the correctness of Dr. Gray's views in having founded the 

 genus. 



The shell of B. tentaculata is conically turbinated and ventri- 

 cose, delicately coloured with a semitransparent fulvous green; 



