5 
Measurements 
Cat. No. 
2881 
2881 
2881 
3144 
3144 
immat. 
2881 
immat. 
2881 
immat. 
3144 
juv. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
mm. 
Maximum diameter •. . . 
17-2 1 
17-3 
16-4 
16-3 
15-4 
15-3 
14-8 
12-4 
Minimum diameter. 
15-3 
150 
14-6 
14-2 
13-7 
13-7 
12-5 
11-3 
Diameter umbilicus 
2-0 
2-2 
2-4 
2-6 
2-2 
2-4 
1-8 
1*7 
Altitude. 
14-1 
13-2 
130 
12-3 
11-7 
110 
110 
9-2 
Number of whorls 
5f 
5* 
5i 
51 
51 
5* 
5i 
5 
1 Lip broken. 
Remarks The whereabouts of Dawson’s original material of his Helix 
Umitaris, or even the certainty of its existence, is unknown. Although the 
original description is very good it was unaccompanied by a figure, and 
there has been much speculation as to the exact systematic position of the 
species. The writer had always supposed the type to be in the collection 
of the Geological Survey at Ottawa but Mr. Johansen, who has been to 
considerable trouble in the matter, states that he has been quite unable to 
locate it there, and he met with only negative results in ail attempts to 
push the quest further. Information has been obtained that the type is 
not in the British Museum, nor in the Redpath Museum of McGill Univer- 
sity, nor in any of the other collections in Canada or the United States 
where it has been thought worth while to make inquiry. 
The loss of the type material is not, however, so disastrous as it might 
be, since the Survey possesses other specimens as herein described, collected 
by J. B. Tyrrell of Toronto, who was assistant to Dr. Dawson on a sub- 
sequent exploration of the same region, and who writes {in litt.) that they were 
obtained from the same general locality and most probably from the ident- 
ical swamp where Dawson collected the originals. 1 Likewise Mr. Johansen 
has ascertained that there are five specimens of “ Helix Umitaris Dawson,” 
collected by the North American Boundary Commission, in the British 
Museum. 
The accord of the present specimens with the original description is 
reasonably complete throughout, and hence the writer’s description given 
above may be taken as merely amplifying that of Dawson. The number 
of whorls, however, seems usually slightly more than he states (5§), so his 
specimens would not appear to have been entirely characteristic with re- 
spect to this detail. 
1 “Dr. Dawson found very few specimens of this species near the shore of Waterton lake in 
1874, when he was geologist on the British-North American Boundary Commission .... In 
1883 I was acting as assistant to Dr. Dawson in his exploration of that portion of the Rocky moun- 
tains lying between the Forty-ninth parallel and the Bow river. Dr. Dawson did most of the 
geological work himself and my duties that year were largely topographical, but at the same 
time I attended to the collection of plants and some small mollusks and Crustaceans. On the 
evening of August 24 we all camped at the north end of the southern and larger of the two parts 
of Waterton lake, and that evening I found near the shore some specimens of ‘Physa lordi.' 
“The next morning, namely August 25, Dr. Dawson went westward with the pack animals 
up the South Kootenay pass, while I went round a short way to a swampy piece of land where, 
around rotten logs, I found several specimens of ‘Helix Umitaris, ’ these doubtless being the ones 
which are now in the museum of the Geological Survey at Ottawa. I believe that I collected 
these specimens on the same swamp on which Dr. Dawson had collected his specimens nine years 
before." {J. B. Tyrrell, in litt.. Sept. 17, 1918.) 
35813 — 2 * 
