614 GEOLOGY OF THE YELLOWSTONE NATIONAL PARK. 



south slope of ridge south of Gray Mountain; saddle in ridge west of 

 south branch of headwaters of Gardiner; north side of Norris road pass; 

 hill southwest of second crossing of Snake River; west end of ridge south- 

 east of mouth of Mink Creek, and 1 mile from head of Swan Lake Valley, 

 on north side of road to Mammoth Hot Springs. 



As supplemental to the published descriptions, it may be stated that 

 the left valve is considerably more convex than the right and that both 

 valves have the same sculpture. The smooth right valve figured by Whit- 

 held 1 is either exfoliated or, possibly, another species. The anterior ear in 

 that figure is different in form from that of C. bellistriatus, as may be seen 

 on comparison with our figure of a specimen identified by Meek from the 

 Bighorn Mountains. 



The small specimen figured by Hall and Whitfield as C. extenuatus is 

 an immature left valve of this species or of C. pertemiistriatus. 



Camptonectes hellistriatus var. distans n. var. 

 PL LXXII, fig. 13. 



This variety, as far as known, is smaller than the typical form of the 

 species, from which it differs in having the radiating, impressed, punctate 

 lines less closely arranged and consequently- fewer in number, and it also 

 differs in the outlines of the ears. The anterior ear is comparatively broader, 

 with a narrower and deeper byssal notch, and the posterior ear is somewhat 

 smaller and slightly less oblique. Left valve of this variety unknown. 



The specimen figured, which is from near the source of Gardiner 

 River, has the following dimensions : Height, 38 mm.; greatest length, 38 

 mm.; length of hinge line, lil mm. 



The variety has also been collected east of Small Lake, head of Fawn 

 Creek, and in north wall of Fawn Creek. 



Camptonectes pertenuistriatus Hall and Whitfield. 

 PI. LXXII, fig. 11. 



Camptonectes pertenuistriatus Hall and Whitfield, 1S77: Rept. U. S. Geo!. Expl. 40th 



Parallel, Vol. IV, Pt. II, p. 291, PI. VII, fig. 17. 

 Of. Camptonectes extenuatus Meek and Haydeu, 1805: Palreont. Upper Missouri, p. 78, 



PI. Ill, fig. 0. 



The original type in the National Museum is a young individual, 



1 Geol. Black Hills, PI. IV. tig-. 10. 



