12 



CHESTER OSTRACODES OF ILLINOIS 



Species Restricted to the Kinkaid 

 Formation 



Acratia tumida n. sp. 



Bairdia aculeata n. sp. 



Bairdia subtila n. sp. 



Bairdiolites procerus n. sp. 



Macrocypris ovata n. sp. 



Microcheilinella cordata n. sp. 

 *Sargentina asulcata n. sp. 



Sargentina crassimarginata (Croneis and 

 Thurman) 



Glyptopleura adunca Croneis and Thurman 

 *Glyptopleura alvea n. sp. 



Glyptopleura circumcostata n. sp. 



Glyptopleura reniformis Croneis and Thur- 

 man 



Glyptopleura teretiformis Croneis and 

 Thurman 

 *Amphissites exiguus n. sp. 



Amphissites quadratus n. sp. 

 *Amphissites rugosus Girty 



Balantoides reticulatus Croneis and 

 Thurman 



Ectodemites elongatus n. sp. 

 *Ectodemites primus n. sp. 

 *Kirkbya bifrons Croneis and Thurman 



Kirkbya humerosa n. sp. 



Kirkbya intermedia Croneis and Thurman 



Polytylites crassus n. sp. 



Polytylites sublineatus (Croneis and Thur- 

 man) 

 *Deloia serrata Croneis and Thurman 



Deloia tumida n. sp. 



Proparaparchites ovatus n. sp. 



Pseudoparaparchites? aclis Croneis and 

 Thurman 



CHESTER CORRELATIONS 



Ostracodes have been described from 

 three Upper Mississipplan formations which 

 crop out in areas outside of the Illinois basin. 

 These are the Amsden formation of Wyo- 

 ming, the Reynolds formation of West Vir- 

 ginia, and the Fayetteville shale of western 

 Arkansas and eastern Oklahoma. These for- 

 mations all appear, from the data now avail- 

 able, to correlate with the upper Chester El- 

 vira group, although the Fayetteville con- 

 tains several species found in the middle and 

 lower groups. In addition to these forma- 

 tions, a few scattered species have been re- 

 ported from the Bell shale of Ontario, the 

 Batesville sandstone of Arkansas, and the 

 Barnett shale of Texas. 



Amsden formation. — Darton (1904) 

 named the Tensleep and Amsden forma- 

 tions, which occur between the Chugwater 

 and Madison and are exposed along a 

 branch of Tongue River west of Dayton, 

 Wyoming, and considered them to be of 

 Pennsylvanian age. Branson and Greger 



*Species of probable correlative value. 



(1918) established the Mississippian age 

 of the Amsden in the Wind River Moun- 

 tains, correlating it with the Ste. Genevieve 

 formation of the Mississippi Valley. Morey 

 (1935) described 17 species of ostracodes 

 from the Amsden, and followed Branson 

 and Greger's correlation. He stated how- 

 ever "that comparatively little on ostracode 

 faunas of this period has been published 

 and, therefore, it is not easy to make exact 

 correlations." Scott (1935), in connection 

 with a discussion of the Big Snowy group 

 of Montana which immediately underlies 

 the Amsden, considered the Amsden fauna 

 "to be more closely related to the Chester 

 fauna than any other. . . . When this 

 fauna is considered in relation to that of the 

 underlying Big Snowy group, and when 

 stratigraphic relationships are taken into 

 consideration, the Amsden of central Mon- 

 tana must be middle or upper Chester in 

 age." 



A preponderance of the Amsden ostra- 

 code species is found in the upper Chester 

 Clore formation. Of the restricted forms, 

 five Amsden species occur in the Elvira, 

 one in the Homberg and none in the New 

 Design. Although the Amsden fauna is 

 small, the presence of such species in the 

 Clore as Bythocypris amsdenensisj Glypto- 

 pleura m.ulticostatay and Ectodemites warei 

 appears to be particularly significant. 



Reynolds lirnestone. — The Reynolds, de- 

 fined as a member of the Bluefield forma- 

 tion of the Mauch Chunk "group" by Re- 

 ger (1926), crops out in Monroe County, 

 southeastern West Virginia. It, with the 

 overlying Ada and Talcott members, was 

 considered to be the equivalent of the Clore 

 formation. Coryell and Sohn (1938) de- 

 scribed 13 ostracode species from a shale 

 bed near the top of the formation exposed 

 in a quarry near Morgantown, some dis- 

 tance from the type locality. They attempted 

 no correlation other than that shown on a 

 columnar section which gives the members 

 of the Bluefield and Greenbrier groups. 

 The only tie with the Illinois formations 

 given in the section is the Bethel sandstone 

 which is shown between Fredonia below 

 and Gasper above, and is erroneously corre- 

 lated with the "Meramecan." 



An examination of topotype material has 

 more than doubled the number of species, 

 bringing the total number of known spe- 

 cies (exclusive of those as yet undescribed) 



