1870 census of Montgomery Co., Ky, Camargo precinct, enumerated 9 Aug, lists on p. 15 as family #100:
Conley, Wm, 30, farmhand; Magie, 25; Annie, 3; George, 5/12, b. Jan. All born in Kentucky.

1880 census of Bath Co., Ky, Owingsville precinct, enumerated 14 June, lists on pp. 22-23 as family #46/47:
Conley, James, 69, laborer, b. Ohio ireland Ireland; Ann, 67, wife, b. Ky Ky Ky; William, 47, (relation column blank), b. Ky Ohio Ky, laborer; Margaret, 32, wife, b. Ky Ky Ky; Annie, 14, dau; George, 11, son; Becky, 9, dau; James, 3, son. All children born ky Ky Ky.

It appears that the census taker was treating William as a head of household, but forgot to bump the family number. Either William should have been numbered as 46/48, or the relationships should have been given with respect to James.