Silpha Coloradensis, n. sp.– Form of inæqualis, but more elongae, black, except the tip of the abdomen, which is orange-rufocus; above clothed with short black hairs. Head densely punctate, the punctures regular over the greater part of the surface, those in front of the inter-antennal line smalll and less distinct; occipital transeverse impression deep; labrum short, broadly emarginate; antennæ black, club four-jointed, the last three joints pubesecnt, the terminal one longer, compressed, tip sinuately rounded. Thorax about one one-half times as broad as long, narrowed anteriorly, sides broadly arcuate in front, more suddenly so behind, basal lobe slightly and very broadly emarginate. Surface somewhat irregular, densely and very regularly punctate, sides somewhat flattened. Scutellum slightly concave, densely puncutred. Elytra as wide as the thorax and fully twice as long, the sides nearly parallel, outer margins distinctly reflexed, apices conjointly rounded, but sinuate externally, punctuation less dense than that of the thorax, each puncture with a recumbent hair.