I think they are descendents of the "Newport" phase? Either way, mosaics are co dominant so breeding a mosaic to a normal will get you half mosaics. Last year I bred an albino banded to a mosaic and got 5 mosaics out of 8 eggs. This year I hope to breed the mosaic to a ghost cal.
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(New website, albinomilksnake.com coming June 2013)