tri merell a

[Mod. Lat., dim in. from Greek trimeres tripartite.] Palæont .: The type-genus of Tri merel lidæ (q.v.), with two species from the Lower and Upper Silurian of Canada. trim-ě-rěl-11-dæ, s. pl. [Mod. Lat. tri merell ( a ); Lat. fem. pl. adj. suff. -ida.] Palæont.: A family of Brachiopod a. Shell inequivalve, calcareous; beaks usually prominent, or sometimes obtusely rounded, and either ma ive or solid, or divided by a partition into two chambers. There is a well-developed hinge-area, and a wide deltidium, bounded by two ridges, the inner ends of which serve as teeth, though true teeth are not present. Each valve is furnished with muscular platforms. The genera are characteristic of the Upper Silurian, and especially of the Guelph Formation of North America.