Characters of the genus Truncatella. 299 
The truncature of its columella excludes also from this genus Margi- 
nella Auricula of Menard de la Groye, (Marg. buccinea, Risso, Hist. Nat. 
IV. p. 232, and also identical according to Férussac with the fossil 
Auricula ringens of Lamarck,) see Féruss. Tabl. Syst. de la Fam. des 
Auricules, p. 109. 
Class, GASTEROPODA. 
Order. PECTINIBRANCHIA. 
Fam. PALUDINIDZ. 
Genus TRUNCATELLA, Risso ; Cyclostomatos species, Drap. et 
Lamarck; Paludine species, Payraud; Turbo, Mont., Turt., &c. 
Tentacula (2 contractilia) cylindrico-conica, brevia, obtusa, basi ! 
distincta, proboscide separata ; oculis sessilibus paullé supra basis angulum 
externum positis. 
Caput proboscidiforme exsertum. Os ad extremitatem proboscidis 
cylindrice, inter tentacula exserte, disciformem, supra emarginatam, 
(sc. bilobam, ob buccas labiales in proboscidem ipsam coadunatas vel 
commutatas. ) 
Pallium collare siphone nullo; orificio ad dextrum corporis, ut in 
Helice, Melampode, Pedipede, &c. 
Pes rotundatus vel ovalis, brevis, minimus, posticus. 
Operculum corneum simplex, i, e. non spirale, ovale, aperturam teste 
omnino claudens.. 
Testa turrita ; adulta cylindrica, decollata vel truncato-obtusa: anfrac- 
tibus distinctis, vel levibus vel transversé costatis. Apertura ovalis, 
brevis ; peritremate continuo. Labrum simplex. Epidermis nulla. 
Animal littorale, amphibium, sed revera marinum et branchiis spirans. 
Ingredienti, discus terminalis proboscidis pro pedis parte antica servit: 
itaque modo feré larvarum Phalenidarum Geometrarum gradibus alternis 
incedit, Testa junior, tereti-acuminata, é pluribus anfractibus quam 
adulta constat: prioribus in plerisque demim (ut in Hel. Bulino decollato ) 
defractis, truncata evadit. ~ 
, 
It is now nearly three years, since the acquisition of a single live (/f 24 
specimen of Cyclostoma truncatulum, Drap., and a long and continued 
observation of its animal, convinced me that it was entitled to rank as a 
distinct genus from any which were then constituted. I had accordingly 
