Snape's House

[ats_fhc3]

No: HPFGUIDX 42600

I'm not sure if this topic has been brought up before, but seeing as 
how my boyfriend and I are debating this, I though I might as well 
ask. 
We are debating as to what house Snape might have been in. 
Logically, he was most likely in Slytherin, but I am lookin for 
evidence that he wasn't. My boyfriend as pointed out Sirius's remark 
about Snape in GoF: "...and he was part of a gang of Slytherins who 
nearly all turned out to be Death Eaters" (pg. 531). I told him that 
this doesn't necessarily mean Snape was in Slytherin, and he could 
have been in Ravenclaw and hung out with Slytherins. 
Does anyone else have evidence supporting or debunking this? 

"the gremlin"