In the APG, there's a sentence explicitly stating that base evolutions for eidolons are already included in the stat blocks (page 59). This explains their varied base speeds: serpents have a speed of 20, bipeds have 30, and quadrupeds have 40.
Thing is--and I realize this is a little nitpicky--I can't find that sentence anywhere in Unchained. I know it's assumed, but did it get left out during the revamp? Or am I just blind and missed it?