While the pictures on this site are not specific to Belize many of the species are in country. There is a False Fer de Lance (Xenodon rabdocephalus) which may be present on the island along with the Fer de Lance (Yellow-Jawed Tommygoff (Bothrops asper).)

http://www.corcovado.org/biology/snakes/snake_pictures.html

Reptiles Rock!