50 SYSTEMATIC ARRANGEMENT 



1. M. melanastoma, Adams, Gen. Moll. t. 22. f. 5, t. 49. f. 1. 



2. M. melanastomoidea, t. 49. f. 5. 



3. M. fibrosa, t. 122. f. 4. 



c. Shell subglobose, solid; aperture moderate. Animal and oper- 

 culum unknown. 



5. Cervina. 



Shell subglobose, solid, polisbed, imperforated ; mouth semi-ovate ; 

 inner lip callows, rounded. 



1. C. fluctuata, Adams, Gen. Moll. t. 22. f. 4, shell only. 



6. Naticina. 



Shell ovate ; whorls striated ; axis perforated ; spire short; mouth 

 ovate, longitudinal. Allied to Stomatia 1 



1. N. papilla, Adams, Gen. Moll. t. 22. f. 7, shell only. 



d. Shell ear-shaped, thin; aperture very large. Operculum very 

 small, rudimentary, horny. Animal : foot very large, tongue- 

 like, often retractile into the shell. 



7. Stomatia. 



Shell depressed, ear-shaped ; spire small ; mouth very large, open ; 

 inner lip thin, slightly reflexed. 



1 . S. Haliotoideum, 1. 1 1 9. f. 3. (Catina Leachii), Adams, Gen.Moll. 



t. 22. f. 8. 



2. S. zonalis, t. 49. f. 6, It. 82. f. 2. 



3. S. Cymba, t. 119. f. 3, t. 118. f. 1. 



4. S. lsevigata, t. 122. f. 5. 



5. S. Reevesii, t. 121. 



6. S. Leachii, Adams. 



The animal of Stomatia only differs from Natica in being much 

 larger in respect to the size of the shell, and in being provided with 

 only a small ovate, horny operculum. The size of the animal differs 

 in various species ; thus, in S. Cymba it is capable of being with- 

 drawn into the cavity of the shell, which is not the case with S. Ha- 

 liotoideum. 



Stomatia Cymba is very common on the sandy coast two or three 

 yards below the lowest tide ; when walking, it elongates and con- 

 tracts the front part of its foot ; only a part of the shell is exposed. 



Stomatia differs from Natica in the small size of the operculum, 

 which escaped the observation of M. de Blainville, but which is very 

 distinctly to be seen in both the specimens he described in the Mu- 

 seum. Blainville described the shell as covered with the mantle, 

 but the mantle is enclosed and the shell is sunk in the foot. — Gray 

 Spic. Zool. ii. 183. 



