Besides the gods mentioned above there were a number with special functions, a few of whom may now be mentioned. Gods connected with, or invoked during, pregnancy and at birth, besides Chalchiuhtlicue, Ciuacoatl, Teteoinnan, Xochiquetzal and the creating deities, were Chalchiuhtlatonac, associated with Chalchiuhtlicue, and Ayopechtli, the goddess of birth proper, who, like Mayauel, is usually represented as seated on a tortoise. To Ixtlilton, the black god, brother of Macuil xochitl, a sacrifice was made when the child first spoke, and he was regarded as the medical god for children. Other gods, already mentioned, with medical functions were Amimitl (dysentery), Macuilxochitl, Xochiquetzal and Nanauatzin (genital affections), Tlaloc (dropsy), Xipe (skin-diseases), Cinteotl (leprosy), Tezcatlipoca and Tlauizcalpantecutli (senders of sickness), Teteoinnan (goddess of healing herbs), and Tzapotlatenan (who discovered the healing properties of turpentine). The various guilds in Mexico, constituted by members of particular trades, held special rites in honour of those gods who were supposed to preside over their daily activities. Space forbids the inclusion of a complete list, since most can be identified from the details given above. One god however deserves especial mention, Yacatecutli, the god of the Pochteca or travelling merchants, who formed a guild of enormous political importance as will be shown later. Every night while on a journey the merchants, who travelled in companies, burnt incense before their staves which, fastened in a bundle, represented his image, and elaborate rites were held in his honour before their departure and on their return. He was associated in worship with Coyotlinauatl, the god of the guild of feather-workers who inhabited the quarter of Amantlan, which was conterminous with the quarter of the Pochteca. Finally a peculiar god, whose function, other than calendrical, is indeterminate, may be mentioned; the bear-headed Tepeyollotl, the “heart of the mountain,” a cave-god. He is often shown with Tezcatlipoca’s mirror, and may be a manifestation of that omnipresent deity.