332 SHELLS AND SHELL-FISH. PART II. 



Geotrochus Sw, Trochiform ; the body- whorl more or 

 less carinated ; the spire pointed and acute ; outer 

 lip thickened and reflected_, inner almost obsolete ; 

 umbilicus almost obsolete, 

 pileus Zool. 111. ii. pi. 91. Ferussacii Lesson, Voy. 8. f. 5. 



PythohelioG Sw. Sub-spiral ; body- whorl large, ven- 

 tricose, and hardly angulated ; spire convex and ob- 

 tuse ; outer lip thickened and reflected, generally 

 separated from the pillar by a sinus ; umbiiicus none; 

 aperture nearly round. 



P. castanea Sw. Bow. Conch, pi. 8. f. 27. 



Geomitra Sw. Conic, thick, obtuse ; the whorls stri- 

 ated, and coronated with tubercles; body-whorl small; 

 aperture very small, circular ; lips united, the outer 

 one thin ; umbilicus small, 

 bicarinata. Zool. Journ. i. pi. 3. f. 7. {fig. 20. p. 166.) 



Gonidomus Sw. Conic, thick, obtuse ; the spiral 

 whorls distorted ; body-whorl contracted ; aperture 

 oval, perpendicular ; the lips thickened ; umbilicus 

 open, but not deep.* 

 ?pagodus. Lesson, Voy. pi. 8. f. 6. {fig. 21. p. 166.) 



Pupa. Shell cylindrical ; the spire much produced ; 

 the middle whorls thicker than the body- whorl ; 

 teeth generally on the pillar, but none on the outer 

 lip ; aperture mostly round. 



Plicadomus Sw. Spire moderate, regular, and thick, 

 but gradually conic ; the tip obtuse ; aperture perpen- 

 dicular ; inner lip wanting ; outer lip semicircular ; 

 the margin dilated and reflected. 



P. sulcata. Chem. 135. f. 1231, 1232. 

 Pupa Lam. Spire thickest towards the middle ; the 

 tip abruptly pointed ; aperture oval ; the lips con- 

 siderably thickened and united ; a single plait gene- 

 rally on the pillar. 



P. mumia. Mart. 153. f. 1439. 

 * This seems to represent Streptaxis. 



