Ischnochitonidae is a large and diverse group of chitons made up of approximately 175 species found worldwide (Rehder 1981). Morphology ranges from ovate to elongate. Ischnochiton valves may be convex to dorsally carinate with low to high elevation. Ornamentation varies from smooth to variously sculptured. Characteristics shared by individuals of this family are the presence of many slits in the insertion plates of the end valves and only 1 or 2 slits in the intermedi¬ate valves, a tail valve that is multifissured, and the non-occurrence of pectinations in the insertion plates (Cochran 1998). Dall (1889b) established the family Ischnochitonidae from the subdivision Ischnoidea. Since then, several families have been proposed in order to reconcile the morphological diversity within the family (Cochran 1998). Iredale and Hull (1927) described 3 families, Ischnochitonidae, Lepidochitonidae, and Callistochitonidae, all of which have been placed into subfamilies of the Ischnochitonidae (Cochran 1998). Presently 6 subfamilies and 27 genera are recognized in the family Ischnochitonidae (Van Belle 1983; Kaas and Van Belle 1985a, 1985b; Cochran 1998). On the Texas coast Ischnochitonidae is currently represented by 2 genera and 3 species.