194 
Kirtley F. Mather 
1897. Spiriferina cristata. Smith, Proc. Am. Phil. Soc., vol. 35, p. 32. 
Lower Coal Measures: Conway County, Arkansas. 
Upper Coal Measures: Sebastian County, Arkansas; Poteau Moun- 
tain, Indian Territory. 
1903. Spiriferina campestris. Girty, Prof. Paper, U. S. Geol. Surv., No. 
16, p. 396. 
Upper portion of Hermosa formation: San Juan region, Colorado. 
Weber limestone: Crested Butte district, Colorado. 
There can be no doubt that the shells from the Morrow group 
subsumed under this head are conspecific with the forms from 
the Hermosa and Weber limestones thus identified by Girty. 
In one specimen there are seven and eight simple plications on- 
either side of the mesial fold and sinus but in the majority of 
cases the number is five and six. The surface markings consist 
of small, close-set pustules which give a coarsely punctate ap- 
pearance to the shell, and near the margin are fine concentric 
lines of growth. 
Comparing this form with Sp. spinosa of the Chester it is 
seen to have a higher cardinal area and more angular plica- 
tions as well as smaller and more closely-set pustules. The two 
species are probably quite distinct. 
The dimensions of two individuals, one of average size and 
one much smaller, are: 
Length from umbonal region of pedicle valve to an- 
terior margin 9.8 mm., 7.4 mm. 
Length from hinge-line to anterior margin 7.3 mm., 5.7 mm. 
Length of hinge-line 10.5 mm., 6.2 mm. 
Greatest width 12.6 mm., '8.9 mm. 
Thickness 7.3 mm,, 5.0 mm. 
Height of cardinal area 2.8 mm., 1.1 mm. 
Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Station 136). Brentwood limestone: vicin- 
ity of Fayetteville, Arkansas (Stations 134, 135, and 147) ; Saw- 
ney Hollow, Oklahoma (Station 210). Kessler limestone: near 
Brentwood, Arkansas (Station 144), Morrow formation: near 
Ft. Gibson (Stations 296 and 301), Choteau (Stations 297, 302, 
306, and 307), Hulbert (Station 299), and Gore (Station 305), 
Oklahoma. 
