Comment 2 for bug 1440448

Based on local tests on OS X 10.7.5, and confirmed by the message shown in Inkscape's status bar in the screenshot the reporter attached, instead of the symbol (or actually a clone (a <use> element referencing the symbol definition in the <defs> section) a bitmap image is pasted if the X11/XQuartz preferences have not been changed as recommended. If the X11/XQuartz setting to "Update Pasteboard when CLIPBOARD changes" is disabled, inserting symbols into the current Inkscape document works as expected.

Please change the X11/Xquartz preferences for the Pasteboard as depicted on the mac-os download page:
http://inkscape.org/en/download/mac-os/
https://inkscape.global.ssl.fastly.net/media/cms_page_media/328/x11pref_pasteboard.png

Underlying issue (conflict between XQuartz's clipboard syncing feature (which is enabled by default) and X11-based apps which use file formats other that text and raster graphics) is tracked in
* Bug #307005 “[OS X] copy & paste inserts a bitmap copy instead of the vector object”
  https://bugs.launchpad.net/inkscape/+bug/307005

Proposing to link as duplicate to bug #307005 (same underlying issue, which affects various aspects of Inkscape, among them symbols).