CANCELLARIA. 95 



formed outer lip does not increase with age. The Canalifera are 

 characterized by having a canal, in distinction from the Pur- 

 purifera, which have only a notch. This family contains the 

 foUowing genera : 



1. Ceeithium. Club-shaped. Fig. 372. 



2. PoTAMis. The same, fresh water. Pig. 377. 



3. Neeinea. The same, with internal folds. Pig. 374. 



4. Teiphoea, Anterior and posterior canals closed, so as 



to presnt three openings. Pig. 375, 376. 



5. Telescopium. Pyramidal, trochiform. Pig. 378. 



6. Pleueotoma. a slit on the outer part of the outer lip ; 



iacluding Clavatula. Pig. 379, 381. 



7. TuEBiNELLA. Three horizontal folds on the columella. 



Pig. 382, 383. 



8. Spieillus. Spire papillary ; one fold on the columella. 

 Pig. 384. 



9. Cancellaeia. Three folds, and internal costse. Pig. 

 385. 



10. Pasciolaeia. Oblique folds, the lowest the largest. 

 Pig. 386. 



11. PusTJs. Pusiform ; no folds on the columella. Pig. 317. 



12. Ptetjla. Pear-shaped. Pig. 388 to 390. 



13. Steuthiolaeia. Outer lip thickened ; sinuated. Pig. 

 391. 



14. E-ANEiiLA. Two rows of varices ; a canal at each extre- 

 mity of the aperture. Pig. 393, 394. 



15. Mtjeex. Three or more rows of varices ; only one dis- 



tinct canal. Pig. 395, 396. 



16. Typhis. A tubular perforation between each varix. Pig. 

 307. 



17. Teitof. Varices not in rows. Pig. 398 to 401. 

 CANCELLAEIA. Lamarck, 1801. (Prom Cancellatus, cross- 

 barred, like wiadow-frames or net work.) Fam. Canalifera, 

 Lam. Entomostomata, BL— Descr. Oval, thick, cancellated; 

 spire generally short, pointed ; aperture sub-ovate, emarginated 

 anteriorly, pointed at the posterior extremity : outer lip marked 



