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 1 7 |          ground). Others have two fins only, for example conger-eels
 2 7 |         of cestreus which has two fins, by its flexion in a fluid
 3 9 |           to fly, the other their fins to swim. Of the latter some
 4 9 |         the latter some have four fins, others which are rather
 5 9 |         for the (missing) pair of fins to complete the movement,
 6 9 |         before. Flat fish use two fins, and the flat of their body
 7 9 | substitute for the absent pair of fins. Quite flat fish, like the
 8 9 |          movement with the actual fins and with the two extremes
 9 10|         corresponding member, the fins, for instance, in fish.
10 15|    attached obliquely; so are the fins in water animals, and the
11 17|        feet serve them instead of fins. They have their legs too,
12 18|           take in water, not air. Fins are useful for swimming,
13 18|  similarly fish have two pectoral fins; again, birds have legs
14 18|     similarly, most fish have two fins on the under parts and near