monster XP question (sahuagin)

[Frost]

Ok, so I just noticed that the sahuagin's XP is "15+9."

I'm looking at the Monster XP Table and it seems like there is no way to get "15+9."

Special abilities only adjust a monster's XP base.

So, since the sahuagin is a 2 HD creature, it's starting base should be 10, with 2 per HP.

Extra abilities affect the XP base, but the XP per HP never changes.

So how did a 2 HD creature get 9 per HP?

Shouldn't the XP base (in this case 10) be increased by the sahuagin's extra abilities, but the XP per HD amount stay the same?

Note, I'm not bitching and am happily using 15+9. I'm just trying to figure this out as I add HD for tougher sahaugin.

[Traveller]

Yeah...15+9 doesn't sound right. Something I'll be making a note of for the near future.

[tylermo]

Serl?

[serleran]

Not my problem. I was asked to not include any XP amounts when writing the monster descriptions and abilities. Because of that, I never submitted my XP calculation proposal.

It should probably be more like 15+3 but I don't have a M&T at hand.