ON THE STRUCTURE OF THE AORTIC VALVES IN SNAKES (REPTILIA, SERPENTES)

Aortic valve morphology was examined in 32 species of snakes represent ing 28 genera and 11 families and a diversity of habitat preferences. The results largely agree with previous studies but include some previ ously undescribed features, such as the cranial displacement of the cu sps in the left aorta in some species and the structure of the opposin g cusps of the interaortic foramen. Few features of the aortic valves are uniform among species. The pattern of morphological variation does not correlate with simple habitat preference (e.g., terrestrial, arbo real); however, some of the variation, particularly in the valves them selves, correlates with taxonomic relationships. We suggest that the p resence of an interaortic foramen, with its associated valve, could re sult in an interaortic shunt of blood that potentially alters hemodyna mics and flow patterns in the systemic circulation of snakes.