Here's Tertullian, also 2nd Century:
http://www.tertullian.org/articles/reeve_apology.htm
CHAPTER XLVIII.
CONCERNING THE RESURRECTION OF THE BODY.
LET us now consider a little the different treatment of a philosopher
and a Christian. If a philosopher affirms, as Laberius from Pytha-
goras has done, that after death the soul of a man departs into a
mule, and that of a woman into a serpent, and turns all the sails
of eloquence to carry this absurd point, shall not he find credit,
and harangue some of you into abstinence even from the flesh of
animals ? And will not many scruple to eat a piece of beef, for
fear of eating a piece of their ancestors ?