6 4 S 



NORTH AMERICAN INDEX FOSSILS. 



Coal measures of Illinois, Indiana, and Missouri. 



XLV. Trepospira Ulrich and Scofield. 

 Early whorls rounded, later with flat shoulder embracing up to 

 the peripheral angulation ; no umbilicus, slit short, band wide and 

 concave ; sutural edge of later whorls nodose. Devonic-Carbonic. 



141. P. rotalia Hall. Devonic. 

 Shoulder of last whorls gently convex, nodes faint. 

 Hamilton of New York. 



142. P. sphaerulata (Conrad). (Fig. 884, c, d-f.) Carbonic. 

 Shoulders flat or slightly concave ; nodes prominent. 



c ; a 



Fig. 884. a, b, Euconospira turbiniformis ; c, Trepospira sphcerulata ; d, e, T. 

 spharulata var. a ;/, var. (5 ; g, T. illinoisensis. (a-e, after White, 13th Ind.; /, g> 

 after Ulr. and Sc, Pal. Minn.) 



Coal measures of the Alleghanies, Indiana, Illinois, Iowa, Mis- 

 souri, Kansas, and Texas. 

 143. P. illinoisensis (Worthen). (Fig. 884, g.) Carbonic. 



Smaller than preceding and more depressed, with greater apical 

 angle ; nodes smaller, round, separated by more than their 

 diameter. 



Coal measures of Kentucky, Iowa, Illinois, Missouri, and 

 ./Vrkansas 



Family MURCHISONIDjE Koken. 



XLVI. Hormotoma Salter. 

 Shell elongate, consisting of from 8 to 14 rounded or subangular 

 whorls, the outer lip with a broad and deep V-shaped notch, but 

 no slit. Band near the center generally obscure, marginated on 

 each side by a delicate raised line. Ordovicic-Devonic. 



