84 GUIDE TO THE FOSSIL REPTILES, AMPHIBIANS, FISHES. 
Wall-case 
7 . 
Table-case 
12 . 
Wall-cases 
7 , 8 . 
Table-cases 
13 - 10 . 
water teleosteans. Ccelacanthus is Carboniferous and Per¬ 
mian ; TJndina is always Jurassic; Macropoma is Cretaceous, 
Fig. 88.— Restoration of TJndina ( Holophagus ) gulo, from the Lower Lias 
of Lyme Regis; about one-seventh nat. size. (After A. S. Woodward. 
Wall-case 7 and Table-case 12.) ^ 
and is represented in Wall-case 7 by the unique collection 
of Dr. Gideon Mantell, besides later acquisitions from the 
English Chalk. 
Order II.— ACTINOPTERYGII. 
Paddle-like fins may be effective for a sluggish life in 
shallow waters and marshes, but they are less well adapted 
for active swimming away from the shore. Progress in the 
direction of modern fishes therefore only became rapid when 
the fins lost their basal lobe and became light flexible flaps 
of membrane stiffened merely by delicate filaments or fin- 
rays. Thus arose the highest grade of fish-life, known as that 
of the Actinopterygii (“ ray-finned ”). 
Sub-order 1.— Chondrostei. 
The earliest Actinopterygians still resembled the Crosso- 
pterygians of the same period in the excessive hardening of 
the external skeleton, in the heterocercal condition of the 
tail, and in the circumstance that the rays of the median 
fins were more numerous than the pieces of cartilage fixed in 
the flesh to support them. So long as fishes retained this 
combination of characters their internal skeleton never pro¬ 
gressed, and they eventually terminated in the existing 
