THE LINNEAN GENERA. 



30. NERITA.— Plate 35. 

 Animal, a Limax. 



Shell, univalve, solid, somewhat globular, flat beneath ; aperture semi- 

 orbicular : pillar-lip oblique relative to the axis of the shell, flat- 

 tish, truncate, and often toothed ; inner lip frequently toothed or 

 crenulated. 



31. HALIOTIS.— Plate 36. 



Animal, a Limax. 



Shell, univalve, ear-shaped, generally flattish ; spire lateral, very 

 short ; aperture nearly as large as the shell ; disk perforated by 

 a row of pores in a line parallel to the edge. 



32. PATELLA.— Plate 37. 

 Animal, a Limax. 

 Shell, univalve, more or less conic, without a spire. 



S3. DENTALIUM.— Plate 38. 



Animal, a Terebella. 



Shell, univalve, tubular, slightly arched, lessening insensibly towards 

 the extremity, and open at both ends. 



34. SERPULA— Plate 38. 



Animal, a Terebella. 



Shell, univalve, tubular, generally affixed to other bodies, open only at 

 the anterior extremity. 



