118 Marine Shells of the Western Coast of Florida 



more whorls of the spire, is coiled in the direction opposite to that 

 of subsequent growth. The normal revolution of the whorls about 

 the columella is dextral, the apical whorls are sinistral. Fischer 

 stated that there is no known instance of complete sinistrosity 

 among the group. In addition to this unusual character, the apical 

 portion of the shell is tilted from the vertical axis, and the apex with 

 some fraction of the immediately succeeding whorls is more or less 

 depressed into the whorl next below. 



The animals are provided with curious tentacles, shaped like 

 the ears of a donkey and covered within their concavity and near 

 the extremities with delicate, minute hairs which are continually in 

 motion. A long, thick trunk can be extruded from an opening 

 directly above the base of the tentacles, and just external to the 

 base of the tentacles is a pair of sessile eyes. 



Distribution of members of this group is general in warm seas 

 from the intertidal zone to considerable depths. Most species inhabit 

 sandy bottom. 



Genus PYKAMIDELLA Lamarck, 1799 



Subgenus LOJfGCHAEUS Morch, 1875 



Pjraiiiidella207 crenulata (Holmes) PI. 23, fig. 154 



Alt., 15 mm., spire, 9 mm. Shell smoothly elongate-conic, im- 

 perforate; pale brown, polished, translucent, with irregular mottlings 

 of darker and lighter coloring; columella dark brown; apex acute; 

 12 or 13 flat whorls, body whorl rounded; sutures horizontally chan- 

 neled, V-shaped; interior slope and margin crenulate; aperture entire, 

 reniform, outer lip sharp; columella sinuous, two oblique folds; basal 

 margin of outer lip continued into a rounded cord encircling base to 

 upper termination of columellar lip, where it becomes a prominent, 

 flattened plication passing horizontally across the columella; oper- 

 culum corneous, color of shell, notched to accommodate folds of 

 columella. 



Common on sandbars and sandy bottom in shallow water; 

 dredged in Gulf of Mexico at two to six fathoms. Gulf specimens 

 are often uniformly pink. 



^^'' Lat., pyramis, pyramid ; crenulatus, finely notched. 



