SIMPSON — CONTRIBUTIONS TO THE MOLLUSCA OF FLORIDA. 59 



Littorina angulifera Lam. Abundant on the west coast and Keys 

 to Honduras and throughout the West Indies, Bahamas, and Bermudas, 

 often climbing twenty-five feet up mangrove trees. Exceedingly vari- 

 able in size and coloring. The finest specimens were found at Marco. 



Littorina irrorata Say. Abundant in localities only rarely covered 

 by high tide. 



Littorina lineaia D'Orb. Florida Keys ; a very large, heavy, inflated 

 form was found at Key West. 



Littorina zigzag Chem. Key West; Tortugas. Quite variable; 

 some shells nearly jet black and smooth, others with rounded whorls 

 approach very close to L. lineata, with which it probably connects. 



Littori?ia guttata Phil. One shell found at the Tortugas, and an- 

 other at Utilla, Honduras. Mr. Dall identifies them as his species. 



Echinella nodulosa Pfr. Florida Keys. 



Tectarius muricatus Lam. Florida Keys. 



Modulus floridanus Con. West coast. 



Modulus lentil ularis Chem. Common on the Keys; west coast, 

 rare. 



Modulus modulus L. Tortugas. 



Planaxis nucleus Wood. Tortugas. 



Planaxis lineatus Da Costa. Tortugas. 



Litiopa bombyx Kiener. Washed up on Tortugas; very abundant on 

 floating seaweed in the Caribbean Sea. 



Alaba tervaricosa Ad. Tortugas. 



Cerithium atratum Born. West coast; abundant. East coast; re- 

 ceived from Cunningham. 



Cerithium eburneum Brug. Florida Keys. Abunda' t and variable. 



Cerithium algicola C. B. Ad. Florida Keys. I think this is merely 

 a form of the preceding. 



Cerithium semi-ferrugineum Lam. The Keys. 



Cerithium literatum Born. The Keys. Quite variable in form, 

 coloring, and sculpture. Some of the lighter colored forms are very 

 nodulous; others are nearly smooth. 



Cerithium fer rug ineum Say. Abundant on the Keys; rarely found 

 by me on the west coast. Much confusion exists concerning this shell. 

 Pyrazus minimus Gin., is often mistaken for this species, and its so- 

 called variety versicolor of C. B. Adams, which it somewhat resembles in 

 size, form, and sculpture. C. ferrugineum is a solider shell, the aperture 

 is smaller and is lirate within, the nodules are more distinct, and, 

 upon the whole, it is a rougher shell. In Pyrazus minimus the nod- 

 ules are pinched up into longitudinal plications, which become evanes- 

 cent on the lower part of the whorls. I consider the variety versicolor 

 C. B. Ad., of Cerithium ferrugineum, of no value. Mr. Tryon sepa- 

 rates C rissoidaeum Sowb., and states in the manual that it is smaller, 

 always white or yellowish white, and that the sculpture is slightly dif- 



