ON THE RICTAL STRUCTURES OF SOME SNAKES

I describe structures around the corner of the mouth of some snakes. Anilius has a large serous superior rictal gland lateral to the quadrato-maxillary ligament and a large serous inferior rictal gland. Other rictal structures of henophidian grade snakes are mesial to the ligament. Cylindrophis has a medium superior rictal gland and a large inferior gland. Two uropeltines have a large superior rictal gland opening into a rictal bulb with thick folded walls. Xenopeltis has a large superior rictal gland opening by three ducts into a thick walled rictal pocket. Aspidites, Calabaria, Exiliboa, Loxocemus, Tropidophis, and Ungaliophis have a rictal pocket into which open glands that may be mucous or serous. Candoia has glands opening around, but not into, a rictal pocket. Bolyerines show no evidence of differentiated rictal structures. Pareas has a superior rictal gland with serous tubules leading to mucous tubules; supralabial gland lobules also have serous leading to mucous tubules and, from about midway forwards, these lobules form a double row; there is no evidence of a dental gland. Two xenodermatines have supralabial serous tubules leading to mucous tubules, but no evidence of alternating mucous and serous cords. I discuss some alternative evolutionary interpretations.