The rats are to be mummified, stylistically, in the New Kingdom fashion.
The New Kingdom, a late period in ancient Egyptian history, was pretty much the last great hurrah for Egypt. The collapse of the 20th dynasty brought a three-hundred year span of politcal chaos and foreign conquest by the Nubians and Libiyans, later relieved by the Late Period of the Greek Ptolemys. The New Kingdom also includes some of the better known pharaohs, like Akhenaton, (allegedly) Nefertiti**, Tutankhamun, and the Ramesside warrior-kings (Rameses I and his progeny). Ramses II, or Ramses the Great, or Ramses the Insatiable Egomaniac, is more or less responsible with covering Egypt stem to stern in those massive, stony effigies you see in all the vacation brochures.
New Kingdom mummies are a decent compromise. The wrappings and methods are elaborate enough to make things interesting, but without the sudden, steep downturn in mummy quality that became common in the later Greco-Roman period. Plus, there are plenty of well-documented, well-researched examples to work from.
Some New Kingdom mummfications were pretty half-assed. Mummies from that period have been found with intact abdominal organs and brains, for example. Not protocol. I'll try to do a better job.
Further reading:
--A checklist of known, recovered royal mummies, noting their various deformities, dental problems, and states of decay. Needs updating.
--An even better site than the first, with portraits of the surviving royal mummies and theories on the ones that haven't been found.
--AnimalMummies.Com, a project of the Cairo museum. Briefly mentions the massive acts of wholesale fraud embalmers perpetrated on the temple-going public by selling them bundles of rags instead of mummified falcons or cats. Also, insanely weird "victual mummies."
P.S.: Tiresome notes on "the pharaoh Nefertiti" below the cut.
