Air Carrier departure from BOS described ATC taxi clearance phraseology that was in error with regard to runway crossing authority.

Narrative

The airport was taking off Runway 27 and landing Runway 33L. Receiving the departure clearance we went over what we thought may be our taxi route which involved crossing three runways to get to Runway 27; namely Runway 04L; Runway 04R; Runway 33L via Taxiways Charlie and Delta. We pushed back and were positioned behind a A320 waiting to taxi. Ground Control issued a clearance to the A320 as follows 'Runway 27; CHARLIE; DELTA; CROSS Runway 04L; HOLD SHORT OF 33L'. As this was the route both myself and my First Officer were expecting; we discussed the fact that the Controller hadn't instructed the A320 to hold short of Runway 04R. After the A320 had crossed Runway 04L they asked for and received clearance to cross Runway 04R. When the First Officer called for our taxi clearance we received the same instructions. The First Officer asked if we should hold short of Runway 04R and the Controller aknowledged that we should and stated that ATC was only allowed to clear us across one runway at a time stating that he/she thought we had been briefed on this. I expected a taxi clearance that stated 'Runway 27 CHARLIE; DELTA; CROSS Runway 04L; HOLD SHORT OF Runway 04R'. After that I would expect to hear 'CROSS Runway 04R; HOLD SHORT OF Runway 33L' You can't get to Delta without crossing Runway 04R. This is a runway incursion waiting to happen because in low visibility; high workload; your mindset will be on Charlie; looking for Delta and a 33L hold bar. This isn't safe. ATC didn't issue a clearance that should have instructed us to hold short of Runway 04R. ATC in BOS should be educated on the correct way to issue taxi instructions in the future.