The comparative morphology of the mandibular midline raphe in snakes (Reptilia : Squamata)

The morphology of the midline raphe was examined from histological sections cut through the lower jaw of 212 ophidian specimens. These specimens repre sented 184 species selected for their taxonomic breadth and the diversity o f their feeding mechanisms. Variation was observed in each morphological ch aracter examined, and was particularly prevalent in the extent of contact b etween the midline raphe and the adjacent epithelium, the tissue type prese nt in the raphe, and the general shape of the raphe. These morphological va riations showed little correlation with the size of the specimen, and, with a few distinct exceptions, did not assort strongly along taxonomic lines. It is hypothesized that the midline raphe in the ophidian lower jaw perform s, perhaps concurrently, at least three functional roles: an attachment sit e for some of the intermandibular musculature, distention of the cranial ti ps of the dentaries, and mechanical support of ingested prey items. The mor phological variation observed in the midline raphe is presumed to reflect m ultiple solutions to these different functional roles, as well as different emphases on particular functional roles within different taxonomic groups.