Il6 JOURNAL AND PROCEEDINGS 



GENUS PHYSA, DRAP. 



Physa gyrina, Say. 



Variable in size and color ; may be found in streams, and gen- 

 erally around the bay. 



Physa heterostropha, Say. 



Variable in size ; same situations as J^. gyrina. 



genus bulinus, adamson. 



Bulinus hypnorum, Linn. 



A few very fine shells taken at Port Dover in a stagnant pond ; 

 may be found in some of the streams in woods ; not so 

 abundant as the two former species ; is of very delicate 

 structure. Ours are small as compared with those taken at 

 Port Dover. 



SUB-FAMILY PLANORBIN.E. 



sub-genus planorbella, halde. 



Planorbis campanulatus, Say. 



Common, Hamilton Bay and Dundas Marsh. 



sub-genus helisoma, swainson. 



Planorbis trivolvis, Say. 



Variable in size and structure, common in the Bay. 



Planorbis bicarinatus, Say. 



Hamilton Bay, not so plentiful as the two former species. 

 Some specimens from near Ottawa are three times the size 

 of any found here. 



SUB-GENUS GYRAULUS, AGASSIZ. 



Planorbis albus, Say. 



Two or three dead specimens from Dundas Marsh ; a special 

 search may prove it to be plentiful. 



Planorbis deflectus, Say. 



Dundas Marsh and Hamilton Bay, 



Planorbis exacutus, Say. 



Dundas Marsh, and occurs sometimes in streams on decaying 

 leaves. 



