142 Marine Shells of the Western Coast of Florida 



base with spiral cords; operculum corneous, light brown. 

 From below tide mark to one and one-half fathoms. 



Cerithiuni floridanum Morch PL 27, fig. 194 



Alt., 30-35 mm. Shell white with spirally striate pattern of 

 brown; thin epidermis; spire elongate, apex acute; sutures not well 

 defined; 10 or 12 whorls crossed by elevated, mterrupted nodular 

 ribs, sharply angled at periphery of whorls; unequal spiral ridges 

 separated by incised lines over entire external surface of shell; a 

 thickened varix opposite aperture; aperture oval, oblique; outer lip 

 thickened, crenulated by spiral sculpture; anterior canal short, 

 oblique; posterior canal defined by fold at upper part of columella. 



C. floridanum is often confused with C. algicola. The former is 

 more slender, with more elongate spire, fewer ribs, about 11 on 

 penultimate whorl — C. algicola has about 16. Sculptural features 

 stronger and more distantly spaced; outer lip thickened. 



From extreme low tide mark to five fathoms. 



Cerithhim muscarum^s* Say PL 27, fig. 198 



Alt., 25 mm. Shell white with fly-specks of chestnut-brown or 

 almost uniformly brown; apex acute; sutures incised, undulating; 10 

 convex whorls crossed by 10 or 11 axial ribs, interrupted at sutures, 

 slightly nodulated by spiral ridges; a strong varix opposite aper- 

 ture; spiral sculpture of equidistant elevated ridges and fine inter- 

 spatial striations over whorls and base; base defined by a strong 

 cord; aperture typical, basal canal reflected to left. 



Abundant on grassy bottoms in shallow water. 



Cerithium rariahile C. B. Adams PL 27, fig. 195 



Alt., 12 mm. Shell dark brown or grayish white; apex and first 

 few turns often white; apex acute; about eight slightly convex 

 whorls; sutures distinct, a little excavated; sculpture of seven or 

 eight beaded spirals on body whorl, three rows on whorls of spire; 

 fine revolving striations in interspaces; a strong varix on body 

 whorl opposite aperture; aperture oval, outer lip sharp at edge, 

 thick and crenulate within; interior of aperture white; anterior canal 

 short, posterior angle of aperture scarcely sinuate; operculum typical. 



-5* Lat., musca, a fly. 



