Upper Cretaceous
Maryland Geological Survey; Clark, William Bullock, 1860-1917; Goldman, Marcus I. (Marcus Isaac), b. 1881; Berry, Edward Wilber, 1875-1945; Gardner, Julia Anna, b. 1882; Pilsbry, Henry Augustus, b. 1862; Bassler, Ray S. (Ray Smith), b. 1878; Stephenson, Lloyd William, b. 1876