566 C. /. MAURY 



The following species have been identified and are in the geological 

 museum of Cornell University. 



Anodontafragilis Lam. (marginata Say) Limnaea elodes Say 



Anodonta grandis Say Physa heierostropha Say 



Anodonta grandis va,r. footiana Lea Planorbis bicarinatus Say 



Lampsilis luteolus Lam. Planorbis deflectus Say 



Lampsilis ventricosus Barnes Planorbis lentus ? Say 



Sphaerium simile Say Planorbis parvus Say 



Pisidium compressum Prime Amnicola limosa Say 



Pisidium virginicum Bourg. Valvata tricarinata Say 



Limnaea palustris Mull. Campeloma decisa Say 



Of these species Sphaerium simile, Pisidium compressum, Planor- 

 bis deflectus, Amnicola limosa, and Valvata tricarinata are the com- 

 monest forms. 



Every one of the species listed has been found, by the writer, now 

 living in Cayuga Lake. But of the five Unionidae, four are Missis- 

 sippi species which are, however, also living now in the St. Lawrence 

 system. Anodonta fragilis is the only one that strictly belongs to the 

 St. Lawrence. Luteolus though originally a Mississippi species has 

 secured such a foothold in the St. Lawrence system as to have become 

 one of the commonest shells of the Finger Lakes. 



On comparing the Cayuga Valley Pleistocene shells with those of 

 the well-known interglacial beds near Toronto, about 170 miles to 

 the northwest of Ithaca, we find the following species common to both 

 deposits. 



Lampsilis luteolus Lam. Planorbis bicarinatus Say 



Anodonta grandis Say Amnicola limosa Say 



Sphaerium simile Say Physa heierostropha Say 



Pisidium compressum Prime Valvata tricarinata Say 



Limnaea elodes Say Campeloma desisa Say 



Planorbis parvus Say 

 Thus more than half the interglacial species found in Cayuga 

 Valley have also been identified in the warm chmate or Don valley 

 beds of the Toronto formation.^ 



But while we find that every one of the interglacial species of 

 Cayuga Valley are now re-established in Cayuga Lake, on the con- 



iSee A. P. Coleman, Amer. GeoL, Vol. XIII (1894), pp. 85-95; Joiirn. Geol., 

 Vol. TX (1901), pp. 285-310; also C. T. Simpson, Froc. U. S. Nat. Mus., Vol. XVI, 

 PP- 591-95- 



