GEOLOGICAL SURVIiY OF THE TERRITORIES. 509 



and suggesting for it the name 0. Wyominfjensis^ in case further com- 

 ])arisons should confirm this suggestion. Siuce that time I have had 

 an opportunity to see many other examples of it at the locality, as well 

 as to examine specimens of the Californian shell in the collection at Sau 

 Francisco, and no longer have any hesitation in regard to the form here 

 under consideration being specifically distinct. Its lower valve has con 

 stantly a much more pointed, produced, and upward-curved beak; 

 while none of the large number of specimeus have the hinge and beak 

 distorted laterally, as is not uucommonly the case in that species. It 

 Las more nearly the characters of the common recent 0. Virginiana, and 

 O. horealis, but also differs from these in having the beak of its lower 

 valve constantly more pointed and produced, as well as curved upward 

 instead of being merely straight, or irregularly distorted. Another 

 marked and constant difference is, that it always has its muscular scars 

 decidedly smaller, in individuals of corresponding sizes, than we see in 

 the recent shells ; while it never shows any traces of the longitudinal 

 ridges or plications often met with in the latter. 



Locality and position. — Point of Kocks, Wyoming Territory, where it 

 is very abundant in a thin bed just above the upper of the four beds of 

 coal observed near the tops of the hills there. Bitter Creek series. 



Anomia (Placunopis *?) GRYPHORHYNCHUS, Meek. 



Anomm grijphorhyiichus, Meek, 1871. Haydeu's Annual Report, p. 375. 

 • Compare Ostrca anomiceformis, Roemer, 1852. Kreid Vou Texas, p. 75, tab. ix, fig. 7 a.-e. 



Since describing this little shell in the report cited above, I have had 

 an op[;ortunity to examine a very laige number of specimens at the lo- 

 cality, and alter returning home ; and from these collections a fuller 

 and more accurate description is giveji below. 



Shell (for an Anomia) of medium size, thin and pearlaceous, a little 

 obliquely subovate, or more or less orbicular in outliue, usually some- 

 what narrowed toward the beak, and more broadly rounded at the op- 

 posite margin, often rather convex, but A^ariable in this resi)ect ; cardi- 

 nal margin arcuate transversely, or very slightly truncated, scarcely 

 thicker than other parts of the shell, and without any proper marginal 

 cartilage-facet. Upper valve, (assuming the shell to be an Anomia,) in 

 the more ventricose individuals, with the umbo somewhat attenuated 

 and curved so as to present the appearance of the un'der valve of a 

 Gryphaxi, excepting that the obtuse immediate apex is not quite mar- 

 ginal. Surface usually appearing smooth, but in well-preserved speci- 

 mens (especially those most depressed in form) sometimes very faint 

 traces of fine radiating stria?, and thin raised lamella3 of growth, may 

 be seen. No scars of attachment observed on any of the specimens. 



Length and breadth of an orbicular specimen, 0.83 inch; convexity of 

 same, 0.33 inch ; breadth of an oval specimen of the same length, 0.03 

 inch ; while there are all gradations between these extremes of form. 



In first describing this species, I was unable to see any traces of mus- 

 cular scars, in any of the specimens then studied, but many of those 

 since collected show them very clearly. They are precisely asin Anomia; 

 that is, there are four impressions, one small one by the side of a little 

 submarginal cartilage pit, close up under the beak, and three others 

 near the middle of the valve, the largest one of the latter being nearest 

 the cardinal margin, and the two smaller ones just below the large one. 

 These three central scars are more or less nearly circular or oval, and 



