PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER Ii! 
Dalmanella perveta (Conrad) = Doleroides pervetus (Conrad) 
D. subaequata (Conrad) = Pionodema subaequata (Conrad) 
Doleroides gibbosus (Billings) 
D. medius (Winchell) = D. winchelli Cooper 
Lingula elderi Whitfield = Pachyglossa elderi (Whitfield) 
Orthis tricenaria (Conrad) = Hesperorthits sp. 
Pionodema uniplicata Cooper 
Plectambonites sericea (Sowerby) = Sowerbyella (not seen) 
Rostricellula ainsliei (N. H. Winchell) 
R. minnesotensis (Sardeson) 
Strophomena incurvata (Shepard) = S. auburnensis Fenton 
Trematis huronensis ? Billings = T. punctostriata Hall 
T. minnesotensis Sardeson 
Zygospira recurvirostris (Hall) (not seen) 
Correlation of Spechts Ferry member.—This member is difficult to place be- 
cause it contains elements of the fauna below but also elements of the Gutten- 
berg above, such as Pionodema subaequata. The abundance of large Pionodema 
and Doleroides suggests assignment to upper Plattin of Missouri and to the Car- 
ters of West Tennessee. This correlation is also borne out by the large Trematis 
which occurs in the top of the Plattin. 
Guttenberg member of Decorah formation.—In northern Illinois this is the “oil 
rock” ; in northern Iowa it is composed of grayish, shaly limestone about 13 feet 
thick; in Minnesota the member consists of the Rhinidictya bed composed of 
soft, dark-greenish shale, and the Ctenodonta bed characterized by pelecypods. 
Brachiopods occurring in the Rhinidictya bed are: 
Crania setigera Hall = Acanthocrania setigera (Hall) 
Craniella ? ulrichi Hall = Petrocrania ulrichi (Hall) 
Dalmanella hamburgensis Winchell and Schuchert (not Walcott) = D. winchelli Cooper 
Idiospira panderi (Billings) 
Leptaena charlottae Winchell and Schuchert = Bellimurina charlottae (Winchell and 
Schuchert) 
Lingula clathrata Winchell and Schuchert = W estonia clathrata (Winchell and Schuchert) 
L. eva Billings 
Orthis tricenaria Conrad = Hesperorthis tricenaria (Conrad) 
O. (Dalmanella) subaequata perveta Conrad = Doleroides pervetus (Conrad) 
O. (Hebertella) bellarugosa Conrad = Glyptorthis bellarugosa (Conrad) 
Pionodema subaequata (Conrad) 
P. uniplicata Cooper 
Plectambonites sericea Sowerby = Sowerbyella punctostriata (Mather) 
Rafinesquina minnesotensis inquassa Sardeson = Opikina inquassa (Sardeson) 
R. prestonensis Salmon 
R. sinclairi Salmon 
R. trentonensis (Conrad) 
Rhynchotrema ainsliei N. H. Winchell = Rostricellula ainsliei (N. H. Winchell) 
R. minnesotensis Sardeson = Rostricellula minnesotensis (Sardeson) 
Rostricellula pulchra Cooper 
Schizocrania filosa Hall 
Strophomena delicatula Fenton 
S. dignata Fenton 
