With light and scanning electron microscopy of vascular corrosion casts, we have observed in Urobatis jamaicensis that the fourth epibranchial arteries do not merge completely with the dorsal aorta. Instead they form a brief anastomosis with a short vessel projecting ventrally from the dorsal aorta and maintain their integrity as separately distinct vessels. Posterior to the anastomosis, the right epibranchial becomes the celiac trunk and left epibranchial becomes the anterior mesenteric artery/posterior intestinal artery. This vascular configuration appears to be unique in elasmobranchs.