STRATIGRArHIC TAXONOMY 623 



tively thick sections. It may be true, especially in the southern exten- 

 sion of the Cahaba Valley where the Conasauga is represented by thin 

 bedded and only moderately argillaceous limestone 1,100 feet in thick- 

 ness. But I feel certain that the Conasauga never includes the Eutledge, 

 despite the fact that it always rests on the Eome. In support of this 

 statement, I would cite the fact noted two pages back that beds often 

 included in the Eome where this formation is in contact with the Cona- 

 sauga contain Eogersville and Nolichucky fossils. Among these are 

 the following brachiopods determined by Walcott : Micromitra aJabamen- 

 sis, Oholus lambornei, 0. minimus, 0. willisi, Lingulella desiderata, L. 

 ino, L. similis, L. tarpa, Dicellomus appalachia, and Wimanella harlanen- 

 sis — all of which, so far as known, are confined to the upper Cambrian 

 as here understood. 



The upper Cambrian west of Mississippi Eiver. — Eopaleozoic marine 

 sedimentation began in Missouri with the upper Cambrian. At the base 

 of this section is the Lamotte sandstone, an irregular deposit of detrital 

 matter filling the hollows of the old land surface and introductory to 

 the Bonneterre dolomite. The latter is followed, apparently, without 

 break by the Elvins formation, which begins with a shale and ends with 

 an earthy magnesian limestone. The last is in unconformable contact 

 with the dolomites of the Ozarkian S3^stem. The sandstone contains 

 Oholus lamhornei, which passes up into the Bonneterre. Associated with 

 it in the latter and in the calcareous shales of the Elvins are Micromitra 

 sp. Paterina cf. stissingensis, Oholus since, Lingulella acutangula, L. 

 similis, L. texana, Dicellomus nanus, D. politusf, Linnarsonella girtyi, 

 Acrotreta microscopica, Billingsella coloradoensis, B. major?, Eoorthis 

 indianola, E. remnicha texana, and E. wicJiitensis. The articulate 

 brachiopods seem to be confined to the lower half of the Elvins, the 

 inarticulate species to the Bonneterre and Lamotte. The total Cambrian 

 section in southeastern Missouri does not exceed 900 feet in thickness ; 

 and all three formations lap out of existence against the pre-Cambrian 

 Saint Francis islands. 



Except that the Bonneterre dolomite part of the section is re])resentcd 

 by glauconitic calcareous sandstones and shales, the upper Cambrian 

 section in the Arbuckle and Wichita Mountains of Oklahoma (Eeagan 

 formation) and in central Texas (the Katemcy) is practically the same as 

 in Missouri. The Eeagan and the Katemcy agree on the whole even 

 better with those of the Deadwood formation in the Black Hills and Big 

 Horn Mountains in South Dakota and Wyoming. The faunas, too, 

 have much in common. Among these are trilobites, but only the 



