TAB. XIL 



CALX carbonata, var. equiaxi-lenticularis* 



Crystallized Carbonate of Lime, lenticular- 

 equiaxecL 



Class 2. Earth. Order 1. Homogeneous. 



Gen. 2. Lime. Spec. 2. Carbonate of Lime. 



Div. 1. Crystallized. Var. 1. Equiaxed. 



1 he figuring of this shell will not only serve a geological 

 purpose, and show a curious crystallization, but help to 

 explain the flattened crystals in the next plate, which are 

 not easily understood, as the lines they form in the draw- 

 ing give but little idea of flatness, and may seem to express 

 the perspective of a cube, especially as we are not yet much 

 accustomed to these representations. 



This is the Helmintholithus Ammonites of Linn. Gmel. 

 v. 3. 411. usually called Cornu-ammonis, of which there 

 are many species found in the petrified state*, abundant in 



* This species and many others are found only in this state, never 

 recent. 



