106 EVOLUTION IN THE PAST 



the voracious dorabs of our own time (Chirocentrus). There 

 were also many spiny-finned fishes. These evidently had 

 an excessive supply of bony substance, and the surplus 

 was finding its way along the fins. The most numerous of 

 the company were closely related to the Beryx of our own 

 time (Hoplopteryx). Others seem to have developed more or 

 less into horse-mackerel (Aipicthys), sea-perches (Prelates), 

 and sea-bream (Pagellus). 



Fishes with the pelvic fins brought forward, and greatly 

 enlarged as if for flying purposes, were also to be seen 

 (Chirothrix). Fishes eel-shaped and therefore degenerate 

 were numerous (Echidnocephalus, Dercetis, etc.) ; and 

 true eels were in existence (Urenchelys). Here also were 

 fishes of the family to which tarpons belong (Elopidce) ; and 

 many other forms were abroad, belonging to families which 

 exist to-day (Albulida, Halosaurida, Scopelidce, etc.). 



In addition to these, there were various bony fishes, 

 divers in form, and of uncertain affinities (Ctenothrissa, etc.). 

 Indeed in late Cretaceous times there was a decided boom 

 in the fish world, resulting from the new anatomy. An 

 analogous outburst of activity may be witnessed on a small 

 scale in human affairs, consequent on some great discovery or 

 invention. 



Notice must now be taken of the lower classes of the 

 marine population. 



CRUSTACEANS Many crustaceans in Jurassic times had become recognis- 

 able as shrimps, prawns, and lobsters. In the Cretaceous 

 Period all these differentiated creatures became more dis- 

 tinctly defined, and of greater variety. New forms of prawns 

 (Hoplophorm, etc.) and various small lobsters (Enoploclytia, 

 Clytia Leachii, etc.) were now in being. Among the latter 

 some essentially resembled the Norway lobster of our own 

 time (Nephrops) : other allied forms were probably in- 

 distinguishable from the modern Crawfish (Palinurus). There 

 were also numbers of lobsters that had taken to embedding 

 themselves in mud (Callianassa). 



But it was in crab-life that the greatest developments 

 were in progress. Crabs, although foreshadowed in far-back 

 times, cannot be said to have expressed themselves un- 



