TORNATINID^E-TORNATINA. 181 



shell characters to the Cylichna group of Scaphandridce. It is there- 

 fore very important to observe the soft parts when they can be 

 obtained, for it is only by such patient observation by local natural, 

 ists that these interesting little snails can be understood and rightly 

 classified. In Tornatinidce some whole genera and subgenera, such 

 as Tornatina and Sao, are still known only by the shells ; and many- 

 species of the other groups are doubtless incorrectly placed at pres- 

 ent. 



Synopsis of Genera. 



Genus TORNATINA A. Ad. 



Shell cylindrical, with conic or flattened spire, the apex projecting 

 and mamillar, sinistral, tilted, at an angle with the body-whorl ; 

 suture channelled. Columella with one fold. 



Genus RETUSA Brown. 



Shell cylindrical, the spire slightly convex, flat or concave, apex 

 intorted ; suture not distinctly channelled. Columella with one fold 

 or none. 



Section Cylichnina Monts. Shell Cylichna-sh aped, with the summit 

 perforated in the centre, spire sunken. Type B. umbilicata Mont. 



Section Pyrunculus Pils. Shell pear-shaped, wide below, narrow 

 above ; spire as in Cylichnina. Type C. pyriformis. 



Genus VOLVULA A. Adams. 



Shell fusiform, the last whorl forming a projecting process above 

 the spire, apical perforation narrow or closed ; aperture as long as 

 the shell, narrow; columella with no distinct fold. 





Genus TORNATINA A. Adams, 1850. 



Tornatina AD., Thes. Conch., ii, p. 554. FISCHER, Manuel, p. 555. 



Shell cylindrical or oblong with conical or flattened spire, the apex 

 projecting and mamillar, sinistral, tilted so that its axis lies at an angle 

 of about 90 with that of the shell. Suture channelled. Aperture 

 long, narrow above, dilated and rounded below, the outer lip arched 

 forward, retreating at suture and base ; columella arcuate, calloused, 

 with one spiral fold at its junction with the whorl. Type T. voluta 

 Q. & G. 



Animal externally as in Retusa (pi. 60, f. 18, T. voluta.} 

 13 



