190 PALEONTOLOGY OF KENTUCKY. 



Surface marked by fine striae of growth, which are turned backward from 

 the suture, and are vertical on the sides of the volution, and on the lower side 

 curve backward to the umbilical area. 



Formation and Locality. In the upper strata of the Devonian limestone, at and around the Falls 

 of the Ohio, where it is exceedingly rare. As Dr. Knapp's collection, which contained the original speci- 

 mens, is sold, I don't think there exists a representative of this species in the Falls Cities. 



Trochonema yandellana. HALLAND WHITFIELD. 



Plate XX., figure 3. 



Trochonema yanaellana, H. and W. 24th Regent's Rep., p. 194 1872. 

 Trochonema yandellana, H. and W. 27th Regent's Rep., pi. 13 1875. 



Shell turbinate ; volutions about five (three of which are shown in the illus- 

 tration), rapidly increasing, carinated ; the last volution becoming ventricose, 

 and marked by seven revolving carinae, including the one bordering the some- 

 what channeled suture ; four of the carinae are distinctly marked by thin, 

 lanceolate nodes, which become more prominent with the increased growth of 

 the shell, while the other three one bordering the suture and two on the lower 

 middle portion of the volution are destitute of nodes in the specimen de- 

 scribed, but it may be that it assumes this character only in an advanced stage 

 of growth. The carinae are situated, one at the suture and one bordering the 

 moderately large umbilicus, with five on the body of the volution, of which 

 two are above the. middle and three below. The spaces separating those bor- 

 dering the suture and the umbilicus from those on the body of the volution, 

 are considerably wider than the .spaces between the intermediate carinae. 

 Aperture rounded, slightly modified by the carinae. 



Surface marked by fine transverse striae of growth, which turn backward 

 as they cross the volution to the umbilicus. 



The illustration on plate 20 is a copy of Prof. Hall's figure in the 27th Reg. 

 Rep., and this description also a copy of Prof. Hall's in the 24th Reg. Rep. 

 At the time when my plates were prepared there was only cne specimen of 

 this species known, which belonged to the .cabinet of the late Dr. James 

 Knapp, and which at that time was not accessible to me. Since then I came 

 myself in possession of a very fine specimen of this species, which differs some- 

 what from Knapp's. Instead of having only four carinae with nodes, as is the 

 case in Knapp's shell, mine has six. The only smooth carina in my specimen 

 is that bordering the suture. There is also a marked difference in the inter- 

 spaces between the carinae ; while in Knapp's shell the distance from the 

 carinae bordering the suture and the umbilicus, to their adjacent one, is larger 

 than the distances between the other carinae, in my specimen the interspaces 

 between the first carina, as which I count the one near the suture, and the 



