19 
Robertson (1674) ; Avon river, Stratford, Ontario, collected by J. P. Uughton. The 
Baker collection contains a specimen from Brown lake, near Saskatoon, Saskatchewan. 
The geographic range is, therefore, from Maine and Montreal west- 
ward to Saskatchewan and southward to northern Wisconsin and Minnesota. 
It apparently replaces trivolvis in Canada with the exception of the lower 
part of Ontario where typical trivolvis is common. 
The type specimens of macrostomum have been thought lost, inquiry 
having failed to locate them in any Canadian or United States repository. 
Recently, however, Mr. A. LaRocque, while examining molluscan material 
in the Perth Municipal Museum, discovered three specimens of a large 
Helisoma labelled in Whiteaves’ liandwriting as from the Toll Gate, Mont- 
real, presented by R. J. Fowler, Esq. The collection was originally in the 
Montreal Natural History Society collection which was presented to 
McGill University, and later given to the Perth Municipal Museum by 
McGill University, The three specimens, fibred on Plate V, measure as 
follows: 
Hill *6; Gr. diam. 25-0; Ap.H. 10-3; D.7-5 mm. (Lower specimen on plate). 
H.11’6; Gr. diam. 25-0; Ap.H. 9-5; D.7-5 mm. (Specimen at left). 
H.ll-5; Gr. diam. 23-5; Ap.H. 10-0; D.7-5 mm. (Specimen at right). 
Height at expanded lip 14-0 mm.; diameter including lip 25-0 mm. (Lower). 
Height at expanded lip 13-1 mm.; diameter including lip 25-0 mm. (Left). 
Height at expanded lip 13*0 mm.; diameter including lip 25*8 mm. (Right). 
The specimens are very light horn colour, the growth lines very 
distinct; lip greatly reflected, with a dark brown line within the aperture; 
5 whorls, 4 whorls showing in the umbilicus; all shells have a varix on the 
last half of the body whorl and all have a white callus on the parietal 
wall. 
In all probability these specimens are the original types upon which 
Whiteaves’ founded his species. On the plate the lower figure may be 
taken as a lectotype since no holotype was designated by Whiteaves. The 
other specimens may be designated as paratypes. The specimens have 
been placed in the National Museum of Canada and bear the numbers 
3869 (lectotype) and 3870 (paratypes). 
Helisoma pilsbr'yi (F. C. Baker) 
Plate II, figures 16-18 
Planorbis binneyi F. C. Baker (not Tryon), Nautilus, XXIII, p. 41 
(1909) ; Trans. Wis. Acad. Arts. Sci., XVII, p. 237 (1911) ; Tech. 
Pub. 4, N.Y. State Coll. For., p. 277, figs. 46, 17-18 (1916). 
Planorbis trivolvis pilsbryi F. C. Baker, Nautilus, XXXIX, p. 117 
(1926) ; Fresh Water Moll. Wis., I p. 334, PI. xx, figs. 14-21 (1928) . 
Shell axially high; whorls 4^, rather tightly coiled, the body whorl 
well rounded; spire depressed below' the level of the body whorl, which is 
obtusely carinated; umbilical region deep, three full turns of the whorls 
visible; the basal w 7 horls are all rounded, without a trace of carination; 
sculpture of rather distinct riblets, usually rather crowded on the body 
whorl; aperture much higher than wide, rounded below 7 , forming a sharp, 
