278 
Aug. F. Foerste 
one of these specimens, collected in 1911, by Aug. F. Foerste. 
The angle between the cardinal and basal margins is nearer 15 
degrees, and the number of transverse plications along the lower 
half of the shell is nearer 4 or 5 in a length of 5 mm. These 
differences lie easily within the range of variation of this species. 
The specimen is numbered 8416 and is preserved in the Victoria 
Memorial Museum at Ottawa, Canada. 
Whiteavesia pholadiformis was described by Hall from the 
Little Bay des Noquets, on the western side of Lake Michigan, in 
the Report on the Geology of the Lake Superior Land District, 1851, 
p. 213, and several figures were presented. 
Among four specimens from the type locality, and belonging to 
the type series. No. 1365, but not figured by Hall, it is possible 
to distinguish two forms. Two of the specimens are quite elon- 
gate; one of these preserves the posterior outline but the part 
anterior to the beak is lacking; the other presents the anterior 
outline but not the posterior outline of the shell. The shell was 
of moderate height anteriorly, and the beak is rather distant from 
the anterior margin. The general outlines of these shells prob- 
ably closely resembled that of Fig. 16 on plate II of the present 
publication. The other two specimens from the type locality 
evidently were higher and more broadly rounded anteriorly, and, 
judging from one of them, a so-called exterior-interior impression, 
also shorter. The transverse plications below the umbonal ridge 
are well developed in both forms, but the post-umbonal plications 
are only moderately developed, as in Fig. 16 on plate II, and 
not as in the form here called divaricata. The more elongate 
forms, resembling our Fig. 16, are regarded as the typical forms 
of pholadiformis. Figure 4 on plate V is one of Hall’s types. 
Forms unquestionably belonging to the Whiteavesia pholadi- 
formis group, and usually identified with that species, occur also 
in the Lorraine of the province of Quebec. They occur associated 
with Strophomena fluctuosa about a mile west of Vars, a short 
distance south of the railroad. They also occur in the upper part 
of the Lorraine along the road, south of the railroad station at St. 
Hilaire. Along the Nicolet River, southwest of Ste. Monique, it 
occurs in the Richmond strata, 97, 110, and 120 feet above the 
lowest horizon containing Strophomena planumbona. It is found 
here also loose at 136, 220, and 430 feet below this Strophomena 
planu7nhona horizon, evidently in strata belonging to the upper 
