WHITE.] PALEONTOLOGY CRETACEOUS FOSSILS. 309 



layers of the same formation at Coalville, Utah ; but it differs in the 

 greater, although slight, elevation of the apex, the nearly straight, 

 instead of cui'ved, border of the inner lip, and its non-polished surface. 



Position and locality. — Cretaceous strata. Fox Hills Groui) ; valley of 

 Sulphui" Creek, near HiUiard Station, Union Pacific Kaih-oad, Wyoming. 



Neritina (Velatella) patelliformis Meek. 



Plate 7, figs. 7 a, 6, c, aud d. 



Neritina (Dostiaf) patellifornm Meek, 1873, An. Rep. U. S. Geol. Suxv. Terr, for 1872, 

 p. 498. 



" Shell smaU, thick, oval or subelUptic ; nucleus nearly posterior and 

 generally more or less elevated above the posterior margin, but always 

 lower than the middle portion of the dorsal region in front of it, directed 

 obliquely backward, and in well-preserved specimens minutely subspLral 

 at the immediate, more or less oblique ajiex ; inner hi) very broad, or 

 haAiug the form of a thick, smooth, convex septum that extends forward 

 more than half the length of the shell ; outer lip thickened, obtuse and 

 smooth withui ; open part of the apertiu'e small and transversely semi- 

 circular. Siuiace with moderately distinct lines of growth. 



" Length of one of the largest specimens found, 0.62 inch ; breadth, 

 0.50 inch ; height or convexity, 0.33 inch." 



This species belongs to an interesting group of ]^eritoid shells, for 

 which Mr. Meek proposed or rather suggested the name Velatella {loe. 

 cit. p. 499). It seems to be a well-defined group, as indicated by the 

 external features common to its species ; and also by the internal char- 

 acteristics as described by me in Wheeler's Expl. and Surv. West of the 

 100th Merid. vol. iv, x>t. 1, p. 189, discovered in a species then supposed 

 to be identical with If. (F.) carditoides Meek, but which, from later com- 

 parisons, seems to belong to the following variety or perhaps to a dis- 

 tinct species. 



At present there are four or five species of this group known, all but 

 one of which occur in the Fox Hills Group, and the other at or near 

 the summit of the Laramie Group. The species appear to have been in 

 part of marine and part of brackish-water habitat. So far as I am 

 aware, no other species of this type besides those here mentioned have 

 ever been discovered; consequently no other comparisons need be made. 



The tj'pical forms of the species here described seem to be quite dis- 

 tinct from any of the other known species of the group, but by the fol- 

 lowing associated variety it api^ears to be connected with If. ( V.) carditoides 

 IMeek, from the bracldsh-water Cretaceous layers, some 800 feet above . 

 the position of these, and at a locality some two miles distant. 



'•'■ Locality and imsition. — Coalville, Utah, from the Cretaceous beneath 

 the lower heavy^ bed of coal mined at that place." 



Neritesta (Velatella) patelllformis var. weberensis. 



Plate 7, figs. 8 a and h. 



Shell small, depressed, almost regularly elliptical in outline, nearly 

 regularly convex above, and nearly flat or longitudinally slightly con- 

 cave beneath ; beak very small, apparently making about one volution, 

 turned a little to the dextral side of the shell, resting upon the thick- 

 ened posterior margin, but not projecting beyond it, the posterior mar- 

 gin being shghtly reflexed so as to obscure the inciu-ved apex ; inner 

 Mp broad, smooth, flat, or concave longitudinally, and slightly convex 



