134 OAKBONIFEROUS PERIOD. 



Maricopa County ; Salt River ; confluence of White Mountain and Black 

 Rivers; and Canon Butte, Arizona; Oquirrli range, near Camp Floyd ; Lake 

 range, on Fairfield road ; west face of Oquii-rli range ; Nortli Fork of 

 Lewiston Cafion, Oquirrli range ; cliff" east of Belleview ; Meadow Creek, 

 south of Fillmore ; North Star district, Picacho range ; near Beckwith 

 Spring, Cedar range ; Rock Canon, Wasatch range, near Provo, and Virgin 

 range, southwest of Saint George, Utah. 



Spirifer striatus Martin, sp. 



The collections contain some examples of Spirifer that are more or 

 less impei-fect, but which are so closely like S. striatus that I am unwilling 

 at present to make any other assignment of them. They are from strata 

 of the Carboniferous period, near Fort Bayard, New Mexico, and the North 

 Star district, Picacho range, Utah. 



They seem to be different from Professor Swallow's variety of S. 

 cameratus before mentioned, and are evidently identical with the shell' 

 referred by Professor Marcou to this species in his Greology of North 

 America, examples of Avhich he obtained in part from localities not far 

 distant from those at which ours were obtained. Specimens of this species 

 were also obtained from the Subcarboniferous strata at Mountain Spring, 

 old Mormon road, Nevada, which are noticed on a previous page. 



Spirifer rockymontanus Marcou. 



Plate XI, fig. 9, a, b, c, and d. 



Spirifer roclci/monfani Marcou, 1858,* Geol. North America, 50. 



Spirifer opimus Hall, 1858, Geol. Iowa, i, pt. ii, 711. 



Spirifer subventricosa McGhesney, 1860, Descr. New Paleozoic Foss., 44. 



Shell very variable in outline, some examples being scarcely broader than 

 long, while the length and breadth of others have the relative proportions of 

 seven to ten ; regularly rounded in front of the hinge, the hinge-line being 

 usually a trifle shorter than the breadth of the shell immediately in 

 front of it; the valves are of almost equal capacity, and more or less 

 gibbous. Ventral valve having a moderately well-defined mesial sinus, 



*See foot-uote on page l'J5 coucerniug date of publication of this (species. 



