Xenosaurus (Gray) Knob-scaled Lizards Cubina Gray 1856:270. Type species, Cubina grandis Gray 1856, by monotypy. Xenosautus Peters 1861 :453. Type species, Xenosaurus fasciatus Peters 186 1. CONTENT. Four species are recognized: Xenosaurus gradis (five subspecies), X. newmanorum, X . plaryceps, and X. rectocollaris. DEFINITION. The species in this genus are medium-sized (maximum SVL to about 120 rnm) xenosaurid lizards with flattened bodies, relatively flat and triangular heads, and short tails

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... (shorter or only slightly longer than SVL). Dorsal scales are heteromorphic, not imbricate, and some are conical or developed into enlarged tubercles separated by small granular scales. Ventral scales are flat, quadrate, and arranged in transverse rows. Head scales are generally small, tuberculate, and sometimes conical or rugose, but may be enlarged along rostra1 and temporal ridges. Supraoculars also are enlarged, flattened, and in a single longitudinal row. The skin of the neck is loose and expanded, producing n at least two gular folds, of which the posterior one has enlarged scales separated from the ventrals by granular scales. Preanal scales are enlarged and separated from ventrals by smaller scales. Dorsal color is brown or black with or without lighter crossbands or irregular dark blotches. A straight, v-, or w-shaped dark neck band is present. A subocular light stripe extends posteriorly onto and transversely across the neck. Tail markings consist of alternating dark and light rings that may or may not be complete ventrally.