COELACANTH FISHES — WHITE 357 



suggests that during this time they lived in the somewhat deeper parts 

 of the seas, to which they had retreated in the face of competition, and 

 where sedimentation would have been slight and the chances of their 

 remains being preserved would therefore have been slim. A similar 

 suggestion was made regarding the living forms when the Latimeria 

 specimen was caught 14 years ago, for it is clear that they inhabit 

 regions not commonly fished. However, this suggestion has been 

 questioned since we now have reason to believe that a few are caught 

 every year in the shallow, rocky waters around the Comoro Islands. 

 Yet the landing of two or three specimens a year in a particular area 

 which is regularly fished does not necessarily mean that the focal 

 point is in that area. Fish do wander, and they also make seasonal 

 migrations — both specimens, we may note, were caught in December. 



300 250 200 15 O 100 so O 



million years _ _ 



DEV. CARBON. PERM.TRIAS.JURASS.CRET.CAINOZOIC 



Figure 2. — Diagram showing the relative number of species of coelacanths recorded from 

 the different periods in the geological succession. The small number shown in the Permian 

 is probably unreal, owing to poor conditions for preservation during that period. (After 

 Prof. F. E. Zeuner, courtesy of Discovery.) 



It is difficult to understand how any creatures so unchanging as the 

 coelacanths could be considered as "missing links," since it is the es- 

 sence of a biological link that it should connect two different types, 

 and that is just what coelacanths did not do. But they do belong to a 

 curious archaic type of fish — the fringe-finned fishes (Crossop- 

 terygii) — that differ in many ways from those with which most people 

 are familiar. 



The average person knows perhaps a score or two of fishes, and 

 these are all very uniform in structure, in spite of great variation in 

 shape and color: they are nearly all of the type known as teleosts. 

 More interesting to the scientist are the lungfishes, bowfins, and gar- 

 pikes, but these are rarely kept except in the larger aquaria in zoos. 



Not all fishlike creatures are really fishes. Apart from the whales, 

 dolphins, and porpoises, which are mammals, and the extinct ich- 

 ■ thyosaurs, which were reptiles, there are the eel-like lampreys and 

 their kin, which belong to a much more primitive group. 



