Several snake species are known to prey on molluscs, and in the Neotropics some examples are already known; e.g., in the recent book on Belizan land snails by Dourson et al. pictures are given of Sibon species consuming a Drymaeus.
By serendipity I found a paper by Sazima & Muscat (2016) on Dipsas snakes in Brazil, which are known to feed on snails and slugs. The first author had reported in the past about the challenges that these molluscs offer to their predator. Snails must be removed from their shell and slugs release plenty of mucus, making snail handling time-consuming and handling slugs poses the risk of sticking to the substratum. Most observations are based on laboratory conditions, but this paper describes how newly hatched snakes are feeding on snails under natural conditions.
The (unwilling) victims in these cases were respectively Bulimulus tenuissimus (d’Orbigny, 1835) and Helicina angulata G.B. Sowerby, 1873. Both observations were made in Sao Paulo state in different forests.
Sazima, I. & Muscat, E., 2016. Shelled baby food: Newly hatched goo‐eating snakes of the genus Dipsas (Squamata: Dipsadidae) prey on snails in nature. – Herpetologia Brasileira, 5 (3): 63-64.