OF MOLLUSCA. 109 



Fam. XVII. TURRITELLADiE. 



Muzzle short, contractile (not retractile), depressed, papillose on 

 the edge ; mouth inferior. Eye-pedicels fixed to the base of the 

 tentacles. Lingual membrane minute, linear. Teeth 3 * 1 • 3 ; cen- 

 tral single, hooked, denticulated ; inner lateral, first broader, recurved 

 and serrulated above ; two outer lateral similar, ligulate, angularly 

 bent, serrulated on each side above. 



Teeth 3*1*3. Tentacles subulate. Eyes basal, external. Mantle 

 fringed on the edge, slightly siphoned in front. Gill single, very 

 long. Foot short, truncate ; opercular mantle simple. Operculum 

 horny, circular, spiral ; whorls many, fringed on the edge. Shell 

 turrited, imperforate, of many whorls ; aperture subquadrate ; outer 

 lip often rather produced. 



Marine. 



§ Mouth of shell subquadrate, simple in front. 



1. TURRITELLA. 



Shell turrited ; whorls convex ; mouth subquadrate ; outer lip 

 simple ; mantle edge bearded ; nape not crested. Operculum cir- 

 cular; edge of whorls striated, fringed. — Adams, Gen. Moll. t. 38. 

 f. 1 a, b. 



1. T. communis, t. 53. f. 7 ; Forbes §• Hanley, B. M. t. J.J. f. 4 ; 



Adams, Gen. Moll. t. 38. f. 1. 



2. T. triplicata, t. 128. f. 6. 



3. T.? rosea, t. 53. f. 1. 



Mantle of Turritella communis loose, ornamented at the upper 

 part with a fringe of seven long and seven shorter strands, the longer 

 ones foliaceous, fimbriated on both edges. Head : a small flat rounded 

 muzzle resting on the foot like Vermetus. Tentacula elongate, sub- 

 ulate; eyes at the external tumid base. Foot very short in front 

 and behind, truncate and scarcely auricled in front. Mouth with two 

 horny plates and a short tongue. Branchial plume single, of long 

 pectinations, which have connection with the fringe of the head ; 

 above them is a range of coarse strands, like the mucous fillets of 

 Buccinum. On the back of the head and neck are two raised white 

 sinuous longitudinal lines, running parallel to the branchial cavity. 

 Operculum horny. They live in tenacious mud, mixed with shelly 

 debris. I believe they live buried and fixed, and can only protrude 

 the head and tentacula from the mass. They have only a very slow 

 progression, occasioned by the shortness of the foot. — Clark, Moll. 

 333 &518. 



Head of Turritella terebra, Mont., small, broad ; muzzle depressed, 

 rather oval, papillose on the edge. Eye-bearers short, rather tumid. 

 Tentacles slender. Foot short, strong, dilated in front, wedge- 

 shaped, slit, shortened behind ; operculigerous lobe simple. The 

 right canal furnished with a lobe. Margin of the mantle formed 

 with a reflexed pinnated fringe in three series. Operculum with a 

 spiny edge. — Loven. 



