>Also, there have been studies regarding the various color forms of Cepaea nemoralis, concerning what relationship shell color and pattern may have to the environment...are certain color forms more abundant in some habitats and less so in others. (Does anyone have the references that I am referring to?? I just remember being told about them in evolution class.) <
Studies on a variably patterned land snail, I think Cepaea, showed that the variable shell patterns worked to confuse visual predators such as birds.  If a bird finds a solid bright yellow shell and starts to look for more like it, he may overlook duller shells with stripes.  Any one pattern that becomes more common attracts the attention of predators, whereupon it becomes rarer.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487 USA
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That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droigate Spa