This looks shifty - an Essence 4, but they make a point of saying the truss rod cover was custom made and is now conveniently devoid of a serial number.  It's listed as 92K7353, but the only proof of that is a close up photo of a piece of scrapwood with the serial written in ink.
 
http://cgi.ebay.com/Alembic-Bass-Guitar-USA-Made-Beautiful-Must-See_W0QQitemZ370166257958QQcmdZViewItemQQptZGuitar?hash=item370166257958&_trksid=p3286.c0.m14_trkparms=72%3A570|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50

The serial number does not appear on the Stolen Instruments list or the News and Announcements page.
 
It may be hand-written in the control cavity.

That bass has already been covered here and here.  
 
Keith