SCALARIID^E. 87 



distinguished the smooth and ribbed forms as Trunca- 

 tella l&vigata and T. costulata, and the young as Fidelis 

 Theresa. The last appears to be the T. Desnoyersii of 

 Payraudeau. Lowe gave this species the name of T. 

 Montagui, his T. truncatula from Madeira being diffe- 

 rent. The young is Macgillivray's Eulima nitidissima. 

 According to Philippi our shell is Cyclostoma concinnum 

 of Scacchi, and the young is Paludina strigilata of 

 Pareyss. The corresponding name for each state of 

 growth bestowed by Leach on this polyonomatous shell 

 are Zeanoe nitida and Glaucothoe Montaguana. Dra- 

 parnaud, in his ' Tableau des Mollusques/ expressed his 

 belief that his Cyclostoma truncatulum ought to consti- 

 tute a distinct genus, an opinion of which Risso un- 

 skilfully availed himself. 



Family XV. SCALAKTID^, (Scalaridce) 

 Broderip. 



S c *lct , H^m^Viv-e,y 

 Genus SCALA'EIA*, Lamarck. PL II. f. 3. 



BODY screw-shaped : mantle plain-edged, forming an inci- 

 pient or slight fold at the base of the shell : head short, snout- 

 shaped, furnished with a cylindrical and retractile proboscis : 

 tentacles awl- shaped, with blunt tips : eyes on short stalks, at 

 the outer bases of the tentacles : foot lanceolate, double-edged 

 in front ; sole grooved down the middle : gills consisting of a 

 single plume. Sexes separate. 



SHELL turreted, longitudinally ridged or plaited, and often 

 also transversely striated : spire elongated and pointed ; apex 

 slightly inflected : mouth nearly round, with a complete and 

 thickened peristome, angulated below : operculum horny, ear- 

 shaped, few-whorled, and having the nucleus on the columellar 

 or inner side of the mouth but not far from its centre. 



* From scala, a ladder. 



