251 



EXPLANATION OF PLATE 26 

 Figure Page 



182. Petaloconchus irreg'ularis (d'Orbigny) 136 



183. Yermicularia knorri (Deshayes in Lamarck) 136 



184. Vermicularia fargoi Olsson 137 



185. Caecum floridanum Stimpson 137 



186. Sleioceras nitidum (Stimpson) 138 



