Possible Clues:

• After half a century it would not be right in water
• New T would not be right to follow L
• The little creature would get abandoned after half a century
• One foot short to the East, by land or water
• That gets left three-quarters in the water
• Slimy creature sometimes put feet on back of settee
• Amphibian, though adroit, died out
• Kind of newt found in clefts
• After half a century it would not be right to be so amphibious
• So new a T gets left to the last