Mesodon thyroidus, from Michigan. This is one of the larger (shell diameter up to 3 cm) land snails of eastern North America. As a pulmonate snail, most of the last (largest) whorl is occupied by the lung. Blood vessels of the lung surface are clearly visible through the shell. All geophile snails have their eyes on the tips of the larger, upper tentacles.
John B. Burch (photographer; copyright holder), Mollusk Division, Museum of Zoology, University of Michigan-Ann Arbor
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