A PORTAGE FAUNA IN THE MACKENZIE RIVER VALLEY. 
5 • 
PELECYPODA. 
, Ontario, clarkei Beushausen. 
Plate I, figure 8. 
Ontaria clarkei Clarke, N.Y. State Mus., Mem. No. 6 1 , pt. 2, p. 288, pi. 7 r 
figs. 10-20. 
The collection includes several somewhat fragmentary specimens; 
which are referred to this species. The two detached valves shown in 
Plate I, figure 8, have about 130 fine radiating strise without concentric 
stride. The general features of the shell are indicated by the figure. 
Horizon and Locality. Simpson shale, 5 miles above Rabbitskin river, 
Mackenzie river. 
Paraptyx cf, Ontario Clarke. 
Plate I, figure 9. 
Paraptyx Ontario Clarke, N.Y. State Mus., Mem, No. 6, pt. 2, p. 262, 
pi. 7, figs. 1-8. 
■% 
A single fragmentary specimen which is comparable and possibly 
identical with this species is shown in Plate I, figure 9, It is marked by 
about one hundred and fifty fine radiating striae without concentric lines. 
The figure fails to show the three or four rather indistinctly defined strise 
at the left of the beak above the angular ridge on the slightly upcurved 
crescent. The very slight angle which these make with the angular ridge 
bordering the crescent appears to be due to the crushing of the shell. 
Horizon and Locality. Simpson shale; Mackenzie river 5 miles above 
Rabbitskin river. 
Buchiola retriostriata V. Buch. 
Plate I, figures 4, 5, and 6. 
Buchiola retriostriata Clarke, N.Y. State Mus., Mem. No. 6, pt. 2, p. 290‘ 
pi. 10, figs. 1-14. 
t *■ H 
This shell shows no material modifications of the features which 
characterize it in the Portage beds of New York, In a few specimens the 
number of ribs is slightly greater than the New York shells ordinarily show. 
The specimen illustrated in Plate I, figure 4, shows seventeen as the maxi- 
mum number which has been observed. The great majority of the shells 
have ten to fourteen ribs marked by the retral curving strise shown clearly 
in Plate I, figures 5 and 6. This is the most abundant species in the 
faunp,. 
Horizon and Locality. Simpson shale; Mackenzie river 5 miles above 
Rabbitskin river. 
Citations of synonomy will be limited usually to a single author, giving figures or descriptions 
of value for comparison. 
61973—21 
