76 



AMMONITES rotiformis. 



TAB. CCCCLUI. 



Spec. Char. Depressed, ribbed, carinated, a 



furrow upon each side of the keel ; inner 



whorls exposed, many ; ribs many, strong, 



each terminating in a tubercle; aperture 



nearly square. 



The sides of this Ammonite are very slightly concave, 



the front is flat with a sunk keel ; the ribs rising m knobs 



just as they reach the front, give the whorls a very 



square aspect ; the ribs and the hollows between them, 



are nearly equal ; the aperture occupies only one sixth 



of the diameter of the shell, and is very little longer 



than wide. 



From the Lyas, near Yeovil ; the specimen is very 

 ruo-jred, about seven inches in diameter ; the figure is di- 

 minished. 



AMMONITES multicostata. 



TAB. CCCCLIV. 



Spec. Char. Depressed, costated, carinated, a 

 furrow on each side of the keel ; mner 

 whorls exposed, few; ribs strong, sharp, 

 numerous, with a tubercle near the end of 

 each ; aperture oblong. 



Much resembhng the last, but not so flat ; the ribs dif- 

 fer in form ; they are more extended over the front and 

 bent forwards from the depressed tubercle near y to the 

 furrow; the length of the aperture is more than one 

 fourth of the diameter of the last whorl ; the sides are 

 not so remarkably flat, as in the A. rotiformis. 



The figure is diminished from an individual 14 inches 

 in diameter, and between 3 and 4 inches thick, lound in 

 Lyas near Bath. 



