536 IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



fera. Stuart Weller's determinations in the monograph on "Mis- 

 sissippian Braehiopoda," Illinois Geological Survey, have been 

 followed in placing Derbya as a synonym of Orthotetes. The 

 identification of Orestes nodosum is made with confidence from 

 Girty's excellent descriptions and figures, without type speci- 

 mens, thus greatly extending the range of this species. Detached 

 stem fragments and plates of crinoids are abundant throughout 

 the whole series of strata. The identification of crinoid species 

 from a single separate plate is extremely hazardous. As Meek 

 states, Erisocrinus and Ceriocrinus can not be distingiiished by 

 detached plates. It is unusual that Fusulina can not be found 

 in any limestone ledge. The writer has in great measure been 

 dependent on the "Final Report on Nebraska," Meek and Hay- 

 den, for his identifieation of species as Meek's well known pale- 

 ontological work in this report was done in the same geological 

 field as the writer's. Where Meek has given descriptions and fig- 

 ures his identification of species is accepted without question. 

 The recent "Fauna of the Wewoka Formation" by Girty has 

 been of great service, althcngh the nomenclature given there has 

 not in all instances been followed, Paleontological nomenclature 

 at present is in a transitory state, and there probably will be 

 many changes in the future. 



The faunal expression is somewhat earlier in type than found 

 in equivalent horizons farther to the southwest according to 

 faunal lists published in other states. It is quite possilile that in 

 the great trough of the Brownville syncline, life conditions in 

 the Pennsylvanian were such that species continued later than 

 in the more abyssal seas of the southwest. 



ESSEX FAUNA— TARKIO. 

 F'usulina secalica. Ambocoelia planoconvexa. 



Lophopliyllum profundum. Heustedia mormoni. 



Ceriocrinus hemisphericus. Meekella striatocostata. 



Rhombopora lepidodendroides. Productus cosiatus. 



Fistulipora nodulifera. Orthotetes crassa. 



Pugnax uta. Spiriferina kentiu'kiensis. 



Marginifera wabashensis. Allorisma terminale. 



Chonetes granulifer. Myalina swallovi. 



Chonetes geinitziana. Pleurotomaria subdecussata. 



ESSEX FAUNA— PRESTON. 

 Fusulina secalica. Penestella perelegans. 



Lophophyllum profundum. Orthotetes orassa. 



Archaeocidaris dinnini. Enteletes hemiplicata. 



Polypora subniarginata. Seminula argentea. 



Fistulipora nodulifera. Chonetes granulifer. 



Rhombopora lepidodendroides. Productus punCtatus. 



Septopora biserialis. Edmondia nebraskensis. 



The dominant fauna of the Preston is bryozoa. Besides the species 

 listed several indeterminata were found. 



