450 C. R. Keyes — Fauna at the Base of the 



ing forms which characterize the beds immediately below the 

 Burlington limestone. At Burlington, too, the Kinderhook 

 and Burlington formations are sharply contrasted lithologically ; 

 while faunally the two horizons are equally well defined. 



Passing southward one hundred miles, to Louisiana, Mis- 

 souri, the same lithological and faunal features are fou'nd as at 

 Burlington. These characters are shown for 50 miles along 

 the great river in this vicinity. 



In the lower bed of the Burlington limestone (Number 12 

 of the section) is found the typical and well marked basal fauna 

 of this formation. Many of the species, however, have a 

 somewhat greater vertical range than at the Iowa localities. 



Among the most characteristic species of Crinoids to be 

 mentioned are : 



Orophocrinus stelliformis (Owen & Shumard). 

 Cryptoblastus melo (Owen & Shumard). 

 Granatocrinus projectus (Meek & Worthen). 

 Rhodocrinus Wachsmuthi Hall. 

 Rhodocrinus Wortheni Hall. 

 Agaricocrinus brevis (Hall). 

 Dorycrinus unicornis (Owen & Shumard). 

 Dorycrinus subaculealus (Hall). 

 Batocrinus aequalis Hall). 

 Batocrinus lougirostris (Hall). 

 Batocrinus elegans (Hall). 

 Actinocrinus proboscidialis Hall. 

 Actinocrinus tenuisculptus McChesney. 

 Physetocrinus ornaius (Hall). 

 Steganocrinus scidptus (Hall). 

 Stegcmocrinus araneolus Meek & Worthen. 

 Platycrinus Arnericanics Owen & Shumard. 

 Platycrinus Burlinytonensis Owen & Shumard. 

 Platycrinus discoideus Owen & Shumard. 

 Platycrinus subspinosus Hall. 



The fauna of this bed (about 15 feet in thickness) is pri- 

 marily a crinoidal one. The above mentioned forms are some 

 of the most important marking the limited horizon. Many 

 •other crinoids as well as brachiopods, corals, gasteropods, etc., 

 are mingled ; but they range upward into other layers more or 

 less extensively. 



Above the basal bed is a slightly thicker member, of an 

 intensely white color (number 13 of the section). It is chiefly 

 encrinital like the other, but in addition contains a larger 

 amount of comminuted shell material derived from molluscan 

 remains. In places the shell fragments predominate, forming 

 a fine shell breccia not unlike the well known coquina rock of 

 Florida ; but it is, however, so compact that good specimens 



