46 FOSSILS AND NON-MARINE MOLLUSKS 



into the lake, but, abstraction made of these, the facies of the remainder is 

 strikingly like that of the Watlings Island group of shells. 

 Common to the Bahama and Haitian lagoons are : 



Mytilus dominguensis Orb. 

 Cerithium degeneralum Ball. 

 Cerithidea tennis Pfr. 



An Anomalocardia occurs abundantty, but it has been less modified than 

 A . leptalea, the place of which in the Haitian list it occupies. It is more like 

 the fossil form from the salt pond on Long Island at Station 7. The most 

 abundant shell by far in the lot is a Cerithium, which occupies much the same 

 place in the Haitian list that G. rawsoni does in the Bahama one, but which is 

 obviously a modification of C. minimum Gmelin. 



What appears to be a species of Parastarte, a Bittium, and a Dentalium 

 complete the Haitian list which, on the whole, gives the impression that the 

 water must be less saline than in the Watlings lagoon, or that it has been in 

 existence a shorter time, so that the surviving species have not reached so high 

 a degree of modification. A careful study of the fauna of all the West Indian 

 salt pans would doubtless give interesting results. 



EXPLANATION OF PLATES. 

 The figures are natural size except when otherwise stated. 



PLATE XI. 



Characteristic Marine Bahama Fossils. 

 FIG. 1. Phacoides pensylvanicus Linne. 

 FIG. 2. Codakia orbicularis Linn6. 

 FIG. 3. Tellina radiata Linne. 

 FIG. 4. Area occidentalis Philippi. 



PLATE XII. 



FIG. 1. Cepolis (Plagioptycha) inaguana Ball, profile; 3/2. See p. 38. 



FIG. 2. Cepolis (Plagioptycha) pharcida Ball, base. See p. 33. 



FIG. 3. Cepolis (Plagioptycha) pharcida Ball, profile. See p. 33. 



FIG. 4. Cerion (Strophiops) rhyssum Ball, normal. See p. 34. 



FIG. 5. Cerion (Strophiops) agassizii Ball. See p. 33. 



FIG. 6. Cerion (Strophiops) rhyssum Ball, depressed mutation, shell not quite 



adult. See p. 34. 



FIG. 7. Area (Barbatia) reticulata Gmelin, interior of left valve; 3/2. 

 FIG. 8. Cepolis (Plagioptycha) agassizii Ball. The outer lip is defective above. 



See p. 32. 

 FIG. 9. Area (Barbatia) reticulata Gmelin, exterior of right valve; 3/2. 



