Shell robust, inflated, subequilateral. Periostracum thick, adherent. Sculpture absent, or of commarginal lirae or riblets. Umbones prominent, prosogyrate. Hinge plate wide, strongly arched, with continuous series of taxodont teeth. Ligament external, mostly opisthodetic. Adductor muscle scars subequal. Pallial line obscure; sinus absent. Byssal gland small. Mantle lobes unfused. Siphons absent, but inhalant region of mantle edge with elongate papillae. Foot with divided papillated planar sole. Gill protobranch, oblique with respect to anterior-posterior axis, with few, widely spaced, thick filaments. Labial palps small, with few ridges on inner surface; palp proboscides elongate. Alimentary canal with large type 1 stomach lined with cuticle; three ducts to the digestive diverticula; style sac conjoined to mid-gut; intestine looping once to right of stomach; rectum passing through ventricle of heart.
A cosmopolitan deep-water family, it differs from the similar-appearing Neilonellidae in lacking siphons and in having a continuous series of teeth. Approximately 40 species are known and date to the Pliocene, but are probably much older. All arc assigned to one genus.

TINDARIIDAE Tindariidae is a small family of bivalves comprised of approximately 40 species within 1 genus. They are a cosmopolitan family of deep-water inhabitants that are closely related to the Neilonellidae but differ in dentition and lack siphons. Elongate papillae on mantle edge replace siphons (Coan et al. 2000). Shells are made up of aragonite, lack nacre, are longer posteriorly, and equivalve; the hinge plate is distinct, with vertical taxodont dentition. Adductor muscle scars are subequal. A pallial line is present but obscure; the pallial sinus is absent (Coan et al. 2000). This family of bivalves has not been recorded from Australia and was not included in Mollusca: The Southern Synthesis. There is some confusion regarding this family; we place this family after the Yoldiidae, which contains the genus Yoldia. Some authors have given precedence to the family Yoldiidae, but authors in Mollusca argue otherwise (Reid 1998; Coan et al. 2000). In Texas Tindariidae is represented by one species, Tindaria amabilis, whose size is approximately 12 mm (½ in).