I love that sign! The folks at IRM did a great job on it.
And, to answer your question, it was called "Water Bug".
A postcard from the ride can be found by searching the web. ED: Brian, we do not post links here.
Saw this on Chicago Day 6/23/2012. Didn't realize it was your newest attraction. Good job. Brought back many found memories.
We had great time at the museum.
Thanks