DEVONIAN AND MISSISSIPPIAN FAUNAS 283 
Mississippi Valley. At intervals this fauna made incursions into the 
Mississippi Valley Basin, as is evidenced by its representatives in the 
Kinderhook odlite at Burlington, Ia., in the Salem limestone, again in 
the Ste. Genevieve, and to some extent also in the Chester. That this 
is not a complete interpretation, however, is shown in the occurrence 
of a group of crinoids described by Miller and Gurley from near Boze- 
man, Mont.,t which strongly suggests the crinoid fauna of the lower 
Osage horizons of the Mississippi Valley. It is not improbable that 
when our knowledge of these faunas in the northwest is expanded, we 
may be able to recognize elements related to most or all of the faunal 
divisions of the Mississippi Valley. The evidence at present available 
suggests that this region occupied a distant part of the same sea which 
was present farther to the southeast, and that there was more or less 
unobstructed means of faunal communication between the two regions. 
From the Lake Valley region in New Mexico, there has been des- 
cribed an early Mississippian fauna? which is a close ally of the fauna 
of the Fern Glen formation at the summit of the Kinderhook in the 
Mississippi River section south of St. Louis. This occurrence idi- 
cates that the Mississippian sea had transgressed at least as far to the 
southwest as New Mexico by the close of Kinderhook time, and that 
means for faunal communication ‘was unobstructed in that direction. 
The Mississippian faunas from Colorado have been described by 
Girty? who has reported on materials collected in nine separate regions 
from the Ouray, Leadville, and Millsap limestones. All of these 
faunas are separated into two groups by that author, both of which are 
considered to be of essentially the same age, early Mississippian, 
probably Kinderhook or early Osage. The composition of the fauna 
is strikingly like that of the Madison limestone of the Yellowstone 
National Park, its relationships being especially with the Chouteau of 
the Mississippi Valley Basin, but the presence of such forms as 
Eumetria marcyi ?, Straparollus cf. spergenensis, Fenestella serratula ?, 
t Bulletin, Ill. St. Mus. Nat. Hist., No. to. “‘ Poteriocrinus bozemanensis P. doug- 
lassi, and Platycrinus douglasst;” ibid., No. 12, “‘Batocrinus douglassi, Rhodocrinus 
douglassi, R. bozemanensis, R. bridgerensis, Platycrinus bozemanensis, P. bridgerenstis, 
Dichocrinus bozemanensis.” 
2 Miller, Jour. Cin. Soc. Nat. Hist., 1V, 306-15; also Springer, Am. Jour. Sci. 
(3), XXVII, 97-103. 
3 Professional Paper, U.S. G. S., No. 16. 
