ABSTRACT
The pineal complex of non-mammalian vertebrates is a directly photoreceptive structure that contains photoreceptor cells similar to those of the retina. In lampreys and most bony fish the pineal complex has two components: a pineal organ and a parapineal organ. Elasmobranchs, as most other vertebrates, generally possess only a pineal organ (epiphysis cerebri). A few vertebrate taxa, including hagfishes and electric rays, have apparently lost both components during evolution (Oksche, 1965; Vollrath, 1981).
