EXPLANATION OF THE MODELS. 
No. 1.—A large extended specimen of calymene bufo, exhibit¬ 
ing the upper surface of the animal. 
No. 2.—The inferior surtace of the same; that of the head 
shows the gullarpouch, and is an exact copy from nature; 
that of the tail is also a copy from the original fossil, except 
the termination of the right horn of the crescent. The feet 
are imaginary. 
No. 3.—The animal coiled up. 
No. 4.—A transverse section this the articulations of the back. 
No. 5.—A portion of the under side of I. gigas. 
No. 6.—A similar part of another trilobite. The entrance to 
the stomach was between the horns of the^crescent. 
