Shinier and Blodgett — Ml. Taylor Region, New Mexico. 65 



Locality and position. — This variety occurs in very great 

 abundance in layers in a dark shaly sandstone, one mile south- 

 west of Casa Salazar at Neck 14. In places it constitutes the 

 mass of the rock. In age the strata are Fort Benton. It is 

 also found quite abundantly southeast of Cabezon at locality 

 B associated with Ostrea anomioldes var. nanus. 



The type specimen is now in the collection of the Boston 

 Society of Natural History ; catalogue number 13,343. 



Lunatia concinna M. and H. 



(Bull. TJ. S. G. S. 108, p. 134.) 



A single specimen of this species was found. 



Locality and position, — In a brownish sandstone of upper- 

 most Fort Benton age. 



Actceon propinquus Stanton. 



(Bull. U. S. G. S. 106, p. 161.) 



Specimen imperfect and only a small portion of the shell 

 retained upon the internal mold. Agrees with the description 

 in size, shape, ornamentation, as far as visible, and in shape 

 and size of aperture. The columella is not visible. 



Locality and position, — Found rarely in the brownish sand- 

 stones at Neck 3 2 northwestern side, in strata of uppermost 

 Fort Benton or possibly Niobrara age. 



Cephalopoda. 



Ammonoidea. 

 Placenticeras placenta Dekay. 



(Bull. U. S. G, S. 106, p. 169.) 



Our specimen measures in width of last whorl 2*6 inches ; 

 in thickness of shell 1*5 inches. It agrees with Meek's descrip- 

 tion in general form, size of umbilicus, nature of volutions, 

 shape of aperture and condition of the surface. There is, how- 

 ever, no evidence of nodes or other prominences, and the 

 periphery is more narrowly truncate than is shown in Meek's 

 figure. Septa not very clearly shown. 



Locality and position, — The single specimen was found in a 

 brownish yellow sandstone twelve miles southeast of Cabezon 

 at locality A. Associated with it was Prionotropis woolgari, 

 a typical Fort Benton species, but the stratigraphic relations in 

 the field are such as to make the formation either uppermost 

 Fort Benton or Niobrara, since Astarte evansi was found in 

 abundance in slightly higher strata a short distance to the 

 northwest, while slightly lower strata to the southeast contain 

 a mixture of Fort Benton and Montana species. 



Am. Jour. Sci. — Fourth Series, Vol. XXV, No. 145. — January, 1908. 

 5 



