go FROM FISH TO PHILOSOPHER 



pterygion = fin) , which had strengthened the bony sup- 

 ports and muscles and developed a ball-and-socket joint 

 that permitted the fin to be moved in a figure-eight mo- 

 tion, until all four fins came to be rotated under the body, 

 lifting the belly clear of the groimd. It was in some form 

 closely allied to the Devonian crossopterygian, Eus- 

 thenopieron (see Figure 7) that the vertebrates first 

 crawled out of the water onto the land. The Crossop- 

 terygii were first cousins to the Devonian lungfishes, but 

 the lungfishes, despite their aerial respiration, must be 

 excluded from a place in tetrapod evolution because of 

 their specialized elongate fins. 



The Eusthenopteron stem also gave rise to the Coelacan- 

 thini, fairly large fresh-water fishes in which a narrow 

 fin base supported a wide web, supplying an adequate 

 fin for swimming but one that was too weak to support 

 the weight of the body out of water. Like the other 

 Devonian and Mississippian fishes, the coelacanths prob- 

 ably breathed air, but in the Triassic they migrated into 

 the sea, and the air bladder, no longer used for respira- 

 tion, became calcified. They disappeared from the fossil 

 record in the Cretaceous, some 75,000,000 years ago, 

 and imtil recently it was accepted that they had become 

 extinct sometime in that period. Then, in December of 

 1938, a trawler working off East London in Cape Prov- 

 ince, South Africa, at a depth of about forty fathoms, 

 brought in a living survivor of this anci^it race. This 

 specimen, named Latimeria chalumniae, was five feet 

 long and weighed one hundred and twenty-seven 

 poimds, and was described as steel-blue in color with 

 dark blue eyes. The find was reported to Miss Courtenay- 

 Latimer, Curator of the East London Museimi, who 

 communicated at once with Professor J. L. B. Smith of 

 Rhodes University College, Grahamstown, but imfortu- 

 nately her letter was delayed for ten days and meanwhile 

 the body had putrefied and had been disposed of, and 



