194 Marine Shells of the Western Coast of Florida 



Haniinoea antilhiriiiii fruadelupensis Sowerby PI. 39, fig. 284 



Alt., to 18 mm. Shell thin, translucent, pale amber or greenish; 

 thin epidermis; ovate-globose, slightly narrowed at vertex; spire 

 involute, vertex imperforate; surface shows irregular growth lines, 

 and almost microscopic, fine, close, revolving striations; aperture 

 narrow above, widely expanded at base; outer lip thin, sharp, ex- 

 tended beyond vertex and recurved to join with a prolongation of 

 the columellar callus; columella deeply arcuate with a small fold 

 above middle. 



Beyond low tide mark — often in tide pools or about the inlets of 

 creeks and bayous. 



Family APLYSIIDAE 



The free swimming animals of this family bear little external 

 resemblance to any gasteropod mollusk. The shell is wholly inter- 

 nal and consists of little more than a subtriangular, shelly plate. 



Genus TETHYS Linne, 1758 

 Tcthys^e* willcoxi Heilprin PI. 55, figs. 364a, b 



Alt., 53 mm; breadth, 38 mm. Subtrigonal shell is thin and flex- 

 ible, translucent, almost flat; inner layer extremely thin, with iri- 

 descent, horny, calcareous consistency; outer layer straw colored, 

 slightly larger than inner layer. Apex is posterior and sharp, the 

 anterior border rounded, shallow notch near the apex. 



The shell is most difficult to extract from the body owing to 

 its delicacy, having the consistency of wet paper when fresh and 

 extreme brittleness when dry. Separating the swimming lobes, a 

 sharp knife is needed to remove the body parts covering the shell 

 which is nearly central and near the surface. The body can only be 

 preserved in alcohol, and even then it soon loses its form and color. 



This mollusk will best be recognized from the animal, locally 

 called sea hare or sea pigeon; 100 to 150 mm. long; soft-bodied, head 

 and neck quite extended but not distinctly separated from the body; 

 mouth with corneous jaws, on the lower, forward end. Earlike, long 



^^* Gr., Tcthys, mythology, wife of Oceanus. 



