Page:Walcott Cambrian Geology and Paleontology II.djvu/92

 of the Stephen formation; west slope of ridge between Mount Field and Wapta Peak, one mile northwest of Burgess Pass, above Field on the Canadian Pacific Railway, British Columbia, Canada.

Collected by Mr. and Mrs. C. D. Walcott, and B. Stuart and Sidney S. Walcott.

Of this species only one specimen and its matrix is known. This indicates that the body was elongate, pear-shaped, and slightly flattened on the ventral surface. Mouth ventral, near the anterior end, and surrounded by a ring of plates. Surface marked by longitudinally radiating lines. Traces of tube feet occur on the ventral surface.

Genotype.—Laggania cambria, new species.

Stratigraphic range.—Limited to a parting in a stratum of dark siliceous shale 2 feet in thickness in the lower portion of the Ogygopsis zone (= Burgess shale) of the Stephen formation as described in 1908. (See the footnote on page 51 of this paper.)

Geographic distribution.—On the slope of the ridge between Wapta Peak and Mount Field, north of Burgess Pass, and about 3800 feet above Field on the line of the Canadian Pacific Railway, British Columbia, Canada.

There is not much that can be added to the brief generic description. The body of the animal is so completely flattened that the tube feet are obscured, the outline of the ventral sole lost, and the concentric bands almost obliterated. It is not practicable to make out the arrangement of the plate-like structure surrounding the mouth, as the calcareous plates, if ever present, have disappeared.

The surface shows indistinct concentric bands, each one of which is crossed by fine longitudinal lines.

Formation and locality.—Middle Cambrian: (35k) Burgess shale of the Stephen formation; west slope of ridge between Mount Field and Wapta Peak, one mile northeast of Burgess Pass, above Field on the Canadian Pacific Railway, British Columbia, Canada.