The nerves are fibrous, and a commencement of the chiasma is certainly present.
From the under side of these, nerves run to the eyes with or without a chiasma or crossing.
At the base of the section are seen the optic nerves and their chiasma.
We know that they are directly connected by fibres that arch round through the chiasma.
In the sharks, rays, chimæras, and Ganoids the two optic nerves are joined in a chiasma as in the higher vertebrates.
chiasma chi·as·ma (kī-āz'mə) or chi·asm (kī'āz'əm)
n. pl. or chi·as·mas, chi·as·ma·ta (-mə-tə), chi·as·ms
A crossing or intersection of two tracts, as of nerves or ligaments.
The point of contact between paired chromatids during meiosis, resulting in a cross-shaped configuration and representing the cytological manifestation of crossing over.