a. (sb.) Anat. and Zool. [f. TRANS- + L. medius middle: cf. MEDIAN.] Passing or situated across the median line of the body; applied to certain muscles in brachiopods. Also as sb. a transmedian muscle. Also Transmedial a.
1876. T. Davidson, in Encycl. Brit., IV. 193/1. Of the shell or valvular muscles … one pair are transmedians, each member passing across the middle of the reverse side of the shell. Ibid. Transmedial or sliding muscles.
1881. Cassell’s Nat. Hist., V. 261. The fifth pair of transmedians controls the movements from side to side of the beak or umbonal regions of the shell.
