67 



of Planorbis hicar hiatus were collected there, and noted in one of tlie 

 reports of this branch. A visit to the lake in August, 1887, resulted 

 in the discovery of a locality in which this variety occurs in great 

 abundance, associated with very large specimens of the shell we have 

 so long called Physa Lordi. This locality lies on the west shore of the 

 lake near the house of a farmer named Gillian. One striking peculiar- 

 ity noticed among the Planorhes was that about five per cent, of the 

 animals were of just such a reddish tint as the most highly colored shells 

 of Unio OGcidens. Specimens which I kept living for a few weeks were 

 losing their rich color when they died. I refer to this with a view of 

 directing attention to the danger of basing any specific differences on the 

 color of the animal itself. Thii" Planorbis from Meech's Lake is of six 

 or eight times the cubical capacity of the same species as found in the 

 Rideau and Ottawa. In our woodland streams occurs a third form, 

 which is stunted in growth and much distorted, owing, no doubt, to the 

 vicissitudes it has to undergo in localities where at times there is a 

 flood running and at other periods scarcely a drop of water. 



Another shell that is well worthy of note is found in abundance in 

 the Eideau River and less commonly in several other streams. It is 

 the species called by authors Planorbis corpule7itus. The true corpu- 

 lentus described by Say is an entirely different shell. That great 

 naturalist found his types in the lake of the Woods, in what is now part 

 of the Province of Ontario. They were lost on the return journey, and 

 until Mr. James Fletcher collected specimens in the original locality in 

 1885, it was, it would appear, generally believed that Say made some mis- 

 take in the figure he gave of the species. Subsequent writers on shells 

 professed to know more about the matter than Say, and gave the name 

 " coi'pulentus " to an entirely different shell — the same species undoubt- 

 edly which occurs so commonly in the Rideau from the Rifle Range up- 

 ward at least to Black Rapids. All along this reach of water the shell 

 occurs in company with the form of Planorbis trivolvis so common every- 

 where in this vicinity. I have iound the two associated not only in the 

 Rideau but in Nepean Bay, Brighams Creek, and the Peche River, in 

 Masham. The shells are in my opinion quite distinct. What I consider 

 a distorted form of the larger shell has been described by Mr. Whiteaves 

 from Montreal, and named Planorbis macrostomus The same form is 



