190 1 ] WhITEAVES — UXGAVA INLAND MOLLUSCA. 223 



PisiDiuM Steenbuchii (Mollcr). 



Eight perfect specimens, which, upon the whole, agree very 

 well with the rather vngue description of this species, without any 

 illustration, in the *' Index Molluscorum Groenlandiae." 



Valvata sincera, Say. 



• About thirty living specimens, in fine condition, with their 

 opercula. 



Many years ago Canadian examples of this species were 

 erroneously referred to Valvatd hiimcnilis. Say ; and Mr. W. G. 

 Binney at one time thought that they should be regarded as a 

 smodth form of Valvata tricarinata. As now understood, the 

 true V. sincera appears to range over nearly the whole of the 

 northern part of this continent. Living or recent specimens of it 

 have been collected at the following localities. In the Province 

 of Quebec, at three different lakes or rivers in the county of 

 Rimouski ; in fresh water streams on the Island of Anticosti ; and 

 in the Lachine Canal at Montreal. In Ontario, at Lake Nipigon ; 

 in Assiniboia, 01 the east fork of Milk River ; and in British 

 Columbia, at two localities in the East Kootenay district. Similar 

 specimens have been found at Great Slave Lake ; at Sturgeon 

 Lake, Athabasca ; and on the Peace and Upper Mackenzie rivers. 

 The species is also knovt'n to occur in great abundance, in a semi- 

 fossil state, in many shell marl deposits in Quebec and Ontario, 

 from Anticosti to Owen Sound. 



Planorbis arcticus (Beck) Moller, 1842. 



Seven specimens, which seem to be referable to this species, 

 though P. arcticus may be only a synonym of P. parvus. Say (1816) 

 which Binney says is found as far to the northward as Moose 

 Factory in James Bay, and Fort Simpson on the Mackenzie River. 



Ottawa, January iith, 1901. 



