DESCKIPTIONS OF SPECIES. 269 



MISSISSIF-FIAN SPECIES. 

 PROTOZOA. 



In th& Aspen monograph Spurr cites " a number of foraminiferal genera from the 

 upper portion of the Leadville limestone of that region. Tliese as determined bj^ 

 Mr. Bagg include Endothyra sp., Nodosinella sp. near N. jyrlscilJa Dawson, Te.rtu- 

 laria s\). similar to T. ffibiosa, Bigenerina sp., Yal/uulina sp., and Lagena sp. near 

 L. jparherina. 



It is of interest to find so large and varied a fauna of this character in the Mis- 

 sissippiau, and it ma}' be mentioned in this connection that in 1899 I cited a small 

 variety of Endothyra in a similar faunal association from the Madison limestone of 

 Yellowstoae National Park. 



None of the fossils mentioned b}' Spurr have^^ come under my observation. 



Locality and horizon. — Leadville limestone; Aspen, Colo. 



CCEIiESTTEBATA. 



ZAPHRENTIS Rafinesque, 1820. 

 Zapheentis tantilla Miller. 



1891. /japhrcntis tanlilla. Miller, Adv. Sheets Geol. Surv. Indiana, 17tli Rept., p. 11, pi. 1, figs. 23, 24. 



Chouteau limestone: Near Sedalia, Mo. 



1892. Zaphreidk tantilla. JNIiller, Geol. Surv. Indiana, 17th Kept., p. 621, pi. 1, figs. 23, 24. 



Chouteau limestone: Near Sedalia, Mo. 

 189.5. Zuphrentix iantUla. Keyes, Missouri Geol. Surv., vol. 4, p. 111. (Date of imprint, 1894.) 



Kinderhook limestone: Sedalia, Mo. 



Burlington limestone: Louisiana and Hannibal, Mo. 

 These pretty little corals seem to be nearer to a form from the Chouteau lime- 

 stone to which Miller gave the name Za'phrxmtls tantilla than to any other of our 

 American species. 



In shape they are conical, elongate, moderately curved. A few constrictions 

 of growth can sometimes be observed, but usualh^ the form is smooth and tapering. 

 Externally this species is distinguished by its .small size and its regular and slender 

 shape. It scarcely ever attains a diameter of over 10 mm., and more often it is onljr 

 5 or 6 mm. The greatest observed length is 17 mm., and in this instance the diam- 

 eter was only about 7 mm. In an example of 10 mm. diameter there are about 32 

 primary septa whose expanded inner ends unite to form a thick wall about the rather 

 large fossula. The latter is centrally situated, but extends to the corallum wall and 

 contains at least one ^septum. The septa arc thickened at their outer ends also and 

 cemented into a massive stereoplasmic wall. The thickened ends and the free inter- 



aV. S. Geol. Surv., Mon., voJ. 31, 1S98, p. 29. 



