OF MOLLUSCA. 105 



Fam. XVI. CERITHIAD.E. 



Rostrum wrinkled, produced. Tongue linear. Teeth 3 • 1 • 3. 

 Tentacula lateral, subulate. Eyes on the outer side of the base. 

 Gills in a single series of cylindrical, rigid plates. Foot short, broad. 

 Operculum horny, spiral. Shell ovate, covered with a thin peri- 

 ostraca. Mouth ovate or subquadrate, more or less channeled in 

 front ; outer lip often expanded. 



* Operculum ovate. 



1. Rhinoclavis. 



Shell ovate, turrited, with rudimentary varices ; aperture ovate ; 

 canal straight, recurved ; pillar lip thickened. Operculum ovate. — 

 Adams, t. 29. f. 7. 



1. R. diemensis, t. 54. f. 5. 



2. R. vertagus, t. 54. f. 3; Adams, Gen. Moll. t. 30. f. 1. Oper- 



culum oblong, subannular. 



3. R. aluco, t. 54. f. 7. 



4. R. vulgatus, t. 52. f. 5, t. 53. f. 6, 8, 9 ? <?, t. 173. f. 3 ; Adams, 



Gen. Moll. t. 29. f. 7. Operculum subspiral. 



5. R. lemniscatus, t. 52. f. 9. 



6. R. brevis, t. 52. f. 8. 



7. R. morus, t. 52. f. 7. 



8. R. Touranii, t. 127 a. f. 9. 



** Operculum semicircular, of few rapidly enlarging whorls. 



2. Cerithium. 

 Shell turrited ; canal slightly recurved. 



1. C. nodulosum, t. 52. f. 9, t. 54. f. 6. 



2. C. lseve, t. 52. f. 6. 



Teeth of Cerithium 3 * 1 ■ 3, dark brown ; central transverse with 

 five denticulations, the central large, broad, the lateral close, smaller ; 

 inner lateral teeth small, oblong, with a sharp tooth on the inner 

 edge ; outer lateral curved, subulate, acute. 



Cerithium varicosum and C. Montagui are found in the brackish 

 water at the mouth of the river Guayaquil. 



Cerithium peruvianum lives under stones at the low water line 

 on the coast of Arica, Peru. 



Cerithium atratum and C. guaranianum are found in the Bay of 

 Rio in sandy places near rocks at low water mark. 



