Ajax POST from Javascript to Rails: How?


I'm new to rails, and have been struggling for a while now on how to get a simple HTTP POST working via a Prototype-based Ajax call to a rails scaffold. I'm performing the POST as follows from javascript:

new Ajax.Request('object/create', {   method: 'post',   parameters: {object : {url: murl, title: mtitle }},   ...

... but my rails application doesn't actually see any of the parameters I'm sending (i.e. url, title).

This leads me to suspect that the way I'm formatting my parameters is wrong, but I can't seem to find any examples of how to do something like this on the web. Can someone help point me in the right direction here?