What's the difference between teretial and tertial?

Teretial

Definition:

(a.) Rounded; as, the teretial tracts in the floor of the fourth ventricle of the brain of some fishes.

Example Sentences:

(1) A part (the Kappenkern des Facialisknies) of the nucleus funiculi teretis is particularly prominent.

Definition:

Example Sentences:

(1) A great variability in the operculum form, in the number of tertial sulci situating on it, in its linear dimensions and superficial area has been stated.
(2) This probably results from the selection during evolution of such variants of amino acid sequences, which are able to provide the functional variability of antigenic determinants, but keep invariant the tertially structure of protein.
(3) Tumor necrosis factor (TNF, also called TNF-alpha) and lymphotoxin (LT, TNF-beta) have 32% homology in their primary structures, and it has recently been clarified that they also have closely related tertially structures.
(4) These results suggest that the tertial structure change of the cleavage site leads to production of unprocessed insulin proreceptors.
(5) The nhp fraction of a smaller molecular weight has a smaller content of alpha-helix (8%) and the greatest polarity of the environment of tryptophan residues; the molecules of this fraction may have a loose tertial structure.