THE KIMMSWICK AND PLATTIN LIMESTONES 
193 
trema rowleyi, in Description of Species) and a multiplicate form 
of Dinorthis of the D. suhquadrata group. Further southward 
and southeastward in Pike county the Buffalo shales are overlaid 
by Silurian strata, so that the Devonian limestones rest on suc- 
cessively lower strata on proceeding from southern Pike County 
north and northwestward across Ralls County. The Buffalo 
shales correspond approximately to the Maquoketa of Iowa. 
The immediately overlying part of the Devonian limestone cor- 
responds closely to the Wapsipinicon of the same state. 
At the same time those upper parts of the Devonian limestone 
section which contain Acervularia appear confined to the more 
northwestern exposures of Ralls County, extending in a north- 
easterly direction from Shiel across the central parts of R 6 W, 
T 56 N. They correspond to the Cedar Valley limestone of Iowa. 
The Edgewood formation of Pike and of the immediately ad- 
jacent counties, of Silurian age, apparently was deposited in a 
restrictied basin separated from the Silurian of Iowa by some 
barrier. During the later Devonian, however, the seas of Pike 
and Ralls Counties may have been connected with those of Iowa, 
but a barrier extending across the southern part of Pike and the 
adjacent parts of Lincoln County may have limited these seas 
southward, cutting them off from the more southern Devonian 
areas of Missouri. 
20. REMNANTS OF EARLY ORDOVICIAN FAUNAS IN THE EARLY 
SILURIAN OF MISSOURI 
One of the most striking features of the Richmond group is the 
recurrence of Trenton, Black River, and earlier types, frequently 
after a long absence during the intermediate Eden and Mays- 
ville strata. In the Fernvale member of the Richmond from 
southern Illinois and in the adjacent part of Missouri, Hehertella 
lineolata Savage belongs to the same generic division as the new 
species described in this paper from the Kimmswick limestone of 
southeastern Missouri as Mcewanella raymondi. In the Thebes 
sandstone of southern Illinois, Conularia delicatula Savage be- 
longs to a group of species known hitherto only from the Trenton 
of New York {Conularia granulata and C. papillata), but in- 
