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FAMILY IANTHINIDJE. 



Shell thin, fragile, turbinated; whitish or purplish; aperture 

 oval or subtetragonal, the columella a little twisted, lip simple, 

 curved. No operculura. 



Animal pelagic, sustained by a vesicular body called the float, 

 and to which the eggs are attached. The float is composed of 

 a mass of vesicles filled with air, the walls resisting, subcartila- 

 ginous, supported by a narrow peduncle, formed by and adhering 

 to the foot. Sexes separate, no copulatory organ. Rostrum 

 proboscidiform ; no jaws ; radula composed of a great number 

 of elongated teeth, no central tooth. Carnivorous. Secretes a 

 purple fluid, which is ejected from the branchial cavity, when 

 irritated. 



Genus IANTHINA, Lam., 1799. 



Head large, muzzle-shaped, eyes not visible or sessile, tentacles 

 forked so that each appears like a pair, foot rather short, the 

 epipodial lobe somewhat elongated and ciliated, branchial 

 plumes two, unequal. 



The float is found in both sexes, and whilst in the female the 

 eggs are usually attached to the lower surface thereof, the 

 animal in some species is viviparous ; embryos taken from 

 the uterus are operculated, the head has a ciliated velum, the 

 C3 r es are large and well pigmented. 



Shell imperforate, without epidermis, fragile, trochiform or 

 turbiniform, nucleus small, styliform, oblique, spire light pur- 

 plish white, base deeper purple ; whorls few, convex, with stride 

 of growth, angular or gathered at the periphery ; outer lip with 

 a sinus in the middle, columella thin, twisted. 



About 30 nominal species have been described, from the 

 Atlantic and Pacific Oceans ; I reduce them to three species, 

 with a few varieties. 



A species is found in the Pliocene of Italy. 



Reeve monographed lanthina in 1858, including 25 species, a 

 portion of which he first described, and Morch, in the Journal 

 3 , (33) 



