INDIANA PALEONTOLOGY. 66. 



complete calix in the type specimen. The first interradials, except the first 

 anal plate, are larger than the first radials, ten sided, nodose and with short 

 ridges to the surrounding plates. Above each of these are two very small no- 

 dose plates, apparently filling the entire upper part of each interradial area. 

 Tne first anal plate is in the ring of the first radials, a little smaller, seven- 

 sided, nodose. Above this plate are three smaller nodose plates, and above 

 these three others much smaller, the specimen preserving three others yet higher 

 in the area. The ventral disk is unknown to the writer. 



The type is in the collection of Mr. G. K. Greene, who found it in the 

 Hamilton Group, near Charlestown, Ind. 



STROPHOST YLUS A M P L U S, N. Sp., (Rowley). 



Plate 23. Fig. S. 



This handsome shell in the height of the spire, and in the less rapidly ex- 

 panding volutions dilfers even more widely than S. Cyelostomus from the typi- 

 cal species of the genus. 



Little can be seen of the aperture from the presence of the adhering stony 

 material and the crushed condition of the lip. but it is probably nearly round. 

 The cross lines of growth are finer than those on S. Cyelostomus, while the lon- 

 gitudinal strictions can hardly be seen without the aid of a glass. 



Shell, subglobose ; volutions five, the last an outer one quite ventrieose; 

 t€8ta thin. 



In general outline our shell is nearer Cyclonema than Strophostylus, but 

 wants the strong revolving ridge-like stria? of the former. The ornamentation 

 is nearer that of Platyostoma than Strophostylus, wanting entirely the lamelhe 

 character of the latter. 



The type is in the collection of Mr. G. K. Greene, and was found in the 

 Niagara formation at Waldron. Ind. 



NATICOPSIS DUBIA, N. Sp.. (Rowley). 



Plate 23. Figs. 9, 10-11. 



Shell rather large, rounded. Volutions about five and expanding somewhat 

 rapidly, the outer whirl being more than three-fourths of the height of the 

 shell, round and ventrieose. 



Aperture more or less rounded or elliptical. 



Foreign, silicious matter adheres to the under side of the shell in such a 



