Page:Walcott Cambrian Geology and Paleontology II.djvu/196

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This species is based on a small slender annelid that has a slender proboscis; its anterior end has a band of hooks and the posterior end a long whip-like appendage that is longer than the body. The body, exclusive of the caudal appendage, is from 25 to 30 mm. in length in the four specimens collected. One 30 mm. long has a width of 2 to 2.5 mm. as it flattened in the shale.

Ottoia tenuis differs from O. prolifica and O. minor in its slender body and long posterior appendage.

Formation and locality.—Middle Cambrian: (35k) Burgess shale member of the Stephen formation, on the west slope of the ridge between Mount Field and Wapta Peak, one mile (1.6 km.) northeast of Burgess Pass, above Field, British Columbia.

The description of the type species includes all that is known of the genus.

Genotype.—Banffia constricta, new species.

Stratigraphic range.—The stratigraphic range is through about no feet of shale or from the lower Phyllopod bed, where it occurs in a hard siliceous shale, up through to nearly the summit of the Burgess shale where the shale is coarser-grained, steel gray in color on fresh surface, and weathering to a dirty buff color.

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.

Observations.—The reference of this genus to the Gephyrea is tentative. With its elongate body and annular lines it resembles Ottoia, and in the absence of interior structure the evidence is too incomplete to refer it elsewhere.

Generic name derived from Banff, name of town on Canadian Pacific Railway, Alberta, Canada.

Body elongate, constricted midway. The anterior and larger section is elongate-spatulate in outline and the posterior section a narrow ellipse truncated at the ends. The constriction between the