Akshat Jain's blog post from 2010 concluded that that I was most likely wrong on in my identification of the land snails. He said, "The land snails that we saw on the Lovell's Island had white colored lobes and black - brown colored lobes. Thus, they most closely resembled the white-lipped snails (Helix albolabris) as well as the brown-lipped snails or grove snails (Cepaea nemoralis). The shells colors and the rings do not seems to classify them in different groups. The colors are merely a way of adapting to the surroundings. However, the color of their lobes are important in determining the kind of snails they are and the group they belong to." I thought this was very informative, thats Akshat!
Rosin, Olborska and Surmacki. (2011). Differences in predatory pressure on terrestrial snails by birds and mammals. Journal of Biosciences. September 2011, 691–699.