Figure 8 in Systematics, evolution and phylogeny of Annelida - a morphological perspective

Figure 8. Macrochaeta clavicornis (Acrocirridae). 2nd pair of pigmented eye, typical multicellular adult eye with converse oriented photoreceptive processes (arrows), lens absent. Pigment cup formed by a layer pigmented supportive cells (psc) penetrated by processes of rhabdomeric photoreceptor cells (prc), pupil formed by unpigmented supportive cells (usc). Cu = cuticle, ep = epidermis, prc = photoreceptor cell, psc = pigmented supportive cell, smv = sensory microvilli, usc = unpigmented supportive cells. Original: I. Dykstra, Osnabrück.