ABSTRACT
Thirty epecimens of the pampas fox (Dusicyon gymnocercus) were injected with Neoprene latex to study the distribution of the internal carotid and vertebral arteries, and their derived vessels, on the ventral surface of the brain. The internal carotid artery and ist rostral and caudal branches were single on both sides in all cases, as was the right middlle cerebal artery; the corresponding left artery was single in 96.7 por cento of the cases and double in 3.3 por cento. The right rostral cerebral artery was single in all cases, and single (96.7 por cento)or absent (3.3 por cento) on the left. The rostral communicating artery was present in 96.7 por cento and absent in 3.3 por cento while the right caudal cerebal artery was sigle in 86.7 por cento and doublein 13.3 por cento but only single on the left. The basilar arterywas single in all cases. The cerebal arterial circle was closed rostrally in 96.7 por cento of the cases and pen in 3.3 por cento but was closed caudally in all animals. The encephalon blood supply was derived principally from the carotid system, but also from the complementary vertebral-basilar system.