Page:Walcott Cambrian Geology and Paleontology II.djvu/141

NO. 4 palpebral lobe small; palpebral ridge narrow, low, and situated so as to cross the fixed cheek obliquely where the downward slope to the front is most marked; postero-lateral limbs long, with a strong furrow within the strong rounded rim; the front of the glabella passes into the broad groove that merges into the upward sloping, narrow frontal limb; frontal rim rounded and marked by rather strong striæ parallel to the front border.

Surface smooth to the unaided eye; a strong lens shows a slight, irregular pitting where the outer surface is intact. The type specimen of the cephalon has a length of 20 mm.

Observations.—This species was at first confused with Chuangia batia. It differs from the latter in the form of the glabella, and the size of the palpebral lobes and frontal limb. The same features distinguish it from Chuangia nitida and C. fragmenta.

Formation and locality.—Upper Cambrian: (C64) upper limestone member of the Kiu-lung group, 2.7 miles (4.3 km.) southwest of Yen-chuang, Sin-t'ai District, Shan-tung, China.

Collected by Eliot Blackwelder.

Only the central portions of the moderately convex cephalon of this species is known. Within the facial sutures the outline is subquadrangular, exclusive of the short postero-lateral limbs. Glabella slightly convex, truncato-conical, with a very slight trace of short, slightly oblique posterior glabellar furrows; the latter are shown more distinctly on the cast of the interior; occipital furrow shallow and clearly defined; occipital ring slightly convex and rather broad toward the center; dorsal furrow shallow at the sides of the glabella.

Fixed cheeks about one-half the width of the glabella, gently convex; palpebral ridges strong, low, and passing obliquely backward to the rim of a rather large palpebral lobe; the latter is a little longer than one-third the length of the cephalon. The frontal limb is represented by the short concave space in front of the glabella which forms a sharp angle in uniting with the frontal limb.

Surface, slightly pitted when seen through a strong magnifying glass. Length of cephalon, 7 mm.

Observations.—This species is much smaller than the type species, Chuangia batia. It differs from the latter in its narrower frontal