The Primitives 



when the animal lay buried in mud, these round openings stuck 

 out into the water and sucked it down to the gills where oxygen 

 was extracted before the water was expelled again through the 

 same spiracles. This device probably helped to make them even 

 more invisible than flatfish over muddy grounds and, taken together 

 with their protective spines, accounted for their great success on 

 many a deep mid- Atlantic Bank where even the halibut was a rar- 

 ity. In such depths the struggle for survival was even more fero- 

 cious than in the shallower water of the North Sea. There was no 

 plankton down there, and innocent grazing like that of the herring 

 was therefore impossible. All the abyssal fishes were therefore 

 given to tigerish attacks on one another and the skates would have 

 been pretty vulnerable to most of the big toothed monsters if they 

 could have been discovered. 



They themselves fed chiefly on invertebrates, on the clam-like 

 bivalves that sucked sustenance out of the decaying fragments of 

 mud. That was why they had those. huge flat crunching teeth, like 

 the molars of a cow, in their grim little mouths. Clams had heavy 

 shells and, before they could be eaten, these shells had to be 

 crushed by the skate. But, once crushed, a succulent meal resul- 

 ted, the same meal as primitive man had fed on, so that his move- 

 ments could be followed by the refuse piles of the molluscan shells 

 left behind him. The skate, however, left no refuse. After splin- 

 tering the shell, he swallowed the whole animal, dissolving a good 

 deal of the hard parts with the acidic juices of his stomach. 



In this, at least, he was like the plaice but the more Jan learned 

 of his structure the fewer other resemblances he could find. The 

 lateral fins of the flatfish were small : a skate was almost all fin, two 

 gigantic triangular flaps of flesh held out by cartilaginous rays. It 

 was wdth his fins that the skate moved. His tail was too narrow, 

 too whip-like, for him to be able to propel himself forward with 

 it, so he undulated above the sea-bottom with fins extended like 

 wings. He flew in an element more dense than any bird could 

 make use of. And he flew remarkably quickly. For these fins were 

 highly muscular. They were the meat of the skate. They were 



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