NORTHERN AND SOUTHERN KINDERHOOK FA UNAS 63 1 



of convenience to be able to refer to them by name, and there- 

 fore I propose for them the generic name Idiodus. The Bur- 

 lington species may be called i". eastmani, and the English 

 River species /. biloba. 

 This fauna of the English River Grit is essentially that of the 

 Chonopectus bed at Burlington, but with certain modifications. 

 Chonopectus fischeri, although present in the fanua, is not one of the 

 most abundant species; in fact, although most of the species at Maples' 

 Mill can be identified with Burlington forms, many of those that are 

 common at Burlington are rare on English River, and, vice versa, 

 rare species at Burlington are in several instances more common on 

 English River. 



In Marshall and Tama Counties, Iowa, in the region of Le Grand, 

 120 miles northwest of Burlington, the entire Kinderhook section is 

 not exposed. Several beds of limestone have been quarried exten- 

 sively, and have afforded an abundance of fossils, the best-known of 

 which are the famous Le Grand crinoids. The faunas of all these 

 limestone beds are closely allied to that of the higher beds at both 

 Burlington and Louisiana. Beneath these limestones, of which the 

 lowest is a white oolite, there is a 20-foot bed of blue argillaceous 

 sandstone 1 rarely exposed, which at Indiantown, about two miles 

 east of Le Grand, is said to be very friable and of a yellowish tone 

 due to weathering. 2 At this latter locality casts of fossils are said to 

 occur, and although none of them have come under the observation 

 of the writer, yet it seems quite possible that they may represent the 

 Chonopectus fauna, and they should be carefully examined with that 

 point in view. 



The known distribution of the arenaceous facies of the Kinderhook 

 fauna under discussion extends along a line having a general north- 

 west-southeast direction, from Kinderhook, Illinois, to Burlington, 

 Iowa, and thence to near Wellman, Iowa — a total distance of nearly 

 140 miles. If the fauna of the bluish or yellowish sandstone near 

 Le Grand should prove to be the same, 60 miles more would be added 

 to its northward distribution. 



The outcrop of the limestone facies of the formation, with its 



1 Beyer, Iowa Geological Survey, Vol. VII, p. 222. 



2 Ibid., p. 223. 



