New Species of Paleozoic Fossils. ] 05 



Plp:urotomaria estella n. sp. 



Shell small, depressed-conical, umbilicate ; volutions about four or 

 five ; ventricose ; regularly enlarging from the apex ; suture line just 

 below the periphery of the volution ; aperture circular. 



Surface marked by sharp, revolving striae, of which ten are above 

 the periphery and ten below on the outer volution, and with a 

 broader and slightly more prominent band on the periphery ; the 

 revolving striae are crossed by fine transverse ones originating at the 

 suture and bending abruptly backward on the upper part of the 

 volution. 



The character of surface marking is quite similar to that of P. 

 lineata of the Hamilton group; but the spire is more depressed, and 

 the volutions enlarge more rapidly. 



Formation and locality. In limestone, above the "Hydraulic 

 beds " at the Falls of the Ohio. Cabinet of Dr. James Knapp. 



Pleueotomaria imitator n. sjp. 



Shell subhemispherical ; spire moderately elevated, consisting ol 

 four or five rounded volutions, regularly increasing from the apex to 

 the aperture, which is subcircular ; rounded below and broadly 

 umbilicate ; suture distinct, not channeled, situated at the periphery 

 of the preceding volution. 



Surface of the upper sides of the volution marked by strong ridges, 

 which have a slight bend just below tfie suture, and thence curve 

 backward to the periphery, gradually increasing in strength from the 

 apex to the outer volution, on the middle of which they are in the 

 ratio of about twenty to an inch ; on the outer half of the last volu- 

 tion they become gradually obsolete, or merge into the growth striae, 

 , which also mark every part of the surface. Below the periphery 

 there are apparently none of the ridges existing. 



This species is very similar to P. lucina in form, being a little 

 more depressed and the volutions less rapidly increasing. The sur- 

 face markings are more nearly like those of P. arata^ while the volu- 

 tions are more ventricose on the upper side, and the periphery is 

 apparently destitute of a band or sinus. 



FoTmatio7i and locality. — In the limestones below the " Hydraulic 

 beds," at the Falls of the Ohio. Cabinet of Dr. James Knapp, and 

 from Major S. S. Lyon, of Jeffersonville, Ga. 



BUCANIA DEVONICA 71. Sp. 



Shell discoid, widely and equally umbilicate on the two sides ; 

 remaining volutions about four, slightly embracing, vertically com- 



