FISHES OF THE CHALK. 
137 
fins have not been observed. The caudal fin, or 
tail, is composed of numerous strong rays. The 
vertebne are about twenty in number : in most 
instances tlie ribs still remain attached. 
Tlie above description is taken from a most 
beautiful specimen, which is figured below. 
ZEUS LEWESIENSIS. 
Abdominales. — The abdominal fishes are more 
frequent in the mineral kingdom, than those of any 
other order ; tliey are distinguished by the ventral 
fins being placed behind the pectoral, or upon the 
abdomen. The remains of three species, belonging 
to as many genera, have been discovered in the 
Sussex chalk, all of which appear to differ from 
any previously noticed, either in a recent or fossil 
state. 
The first appears to be somewhat related to tlie 
