DoUCLASS : ASTROPKCIKN ? MONTAXUS. 7 



as wide as the middle portion of the arm. ( )nly one arm is complete. 

 This has l\vel\e ]iits on each side and they are opposite. From the 

 central i)it to end ot" perfect arm 12 mm. From 

 central pit to marijin of body between the arms 3-5 ' ^' '"'' ^ 



K jl •■••■'> 



It was said l)y those who saw it when first obtained ' '^^^C^f^ f ^*^ ' 



to have possessed little markings on the margins of / ' ^ I 



the arms. The rock was used for years as a step »V^**^^*Vi. ^ 



near the door and if these were present they have ^ ■ • -^^ 



been wholly worn away. ^ 



The rock is a hard, fme-grained calcareous sand- ^'^^- '" ^^^^'''^P'^'' 



. , . , , , . ten? moutamis Doug- 



stone, greenish-grav m color and weathering to , ,,. ^ , 



' *= * ' ^ lass. (No. 601.) 



brown on the suriace. Natural size. 



Below are given determinations of the accompany- 

 ing fossils and notes which were both kindly furnished by Dr. A. E. 

 Ortmann. They are of interest as determining the horizon of the beds 

 and showing the fauna of the Fort Benton near the eastern portion of 

 the mountain region, since much of the Cretaceous of this region has 

 been found to be poor in fossils. 



Fn'oceraml's uxdabundus Meek and Hayden (?). 

 Stanton, Bull. U. S. Geol. Surv., 106, 1893, p. 84, pi. 6, figs, i, 2. 

 (Fort Benton. Upper Missouri Region.) 



Five casts ; smaller than type, but outline and character of sculpture 

 similar ; the undulations, however, are a little more crowded, which 

 may be due to the younger age of our specimens. 

 PixxA LAKES! White (?). 



White, 1 2th Ann. Rep. U. S. Geol. and Geog. Surv. of Terr., 

 Part I., 1883, p. 17, pi. II, fig. I. 



Ridge sixteen miles west of Greeley, Colorado. (Fort Pierre.) 



Reported from South Fork of Old Man River, Canada, by Whit- 

 eaves. Contrib. Can. Pal., Vol. I., part i, 1885, p. 84. Apparently 

 Fort Benton (p. 89). 



One fragrant compared with the type agrees well, but is smaller 

 and more compressed, sculjjture identical. 



Pholadomva papvracka Meek & Hayden (?). 



Stanton, Bull. U. S. Geol. Surv., 106, p. 116, ])1. 26, p. i. 

 Fort Benton group. Upper Missouri region. 

 Three specimens (both valves). 



