Page:Walcott Cambrian Geology and Paleontology II.djvu/194

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With our present information it is not practicable to make a reference of Ottoia to any of the existing orders of the Gephyrea. The presence of an anterior, retractile, or introvertible proboscis, and the elongate cylindrical shape of the body is essentially similar to some of the Sipuncnloidea, but the direct enteric canal, and more or less distinct segmentation is unknown in that order. In this tentative study the ordinal classification will be omitted.

Body cylindrical, elongate; with numerous segments that vary in width posteriorly. Hooks about the mouth and also at the posterior end. Proboscis papillose, introvertible, and with mouth at anterior end. Enteric canal direct from mouth to anus, or possibly with some slight convolutions.

The genus Ottoia is referred to this family, and also, though tentatively, Banffia.

The description of the species O. prolifica includes all the known essential characters of the genus.

Genotype.—Ottoia prolifica, new species.

Stratigraphic range.—The stratigraphic range is limited to a band of dark siliceous shale about 4 feet in thickness forming a part of the Burgess shale member of the Stephen formation.

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 position of Ottoia among the annelids is discussed under the class Gephyrea to which it is tentatively referred (page 127).

Generic name derived from Otto, name of a creek north of President Range, British Columbia, Canada.

Body elongate, tapering at each end when not contracted. It is divided by annular lines into many segments that average seven in a distance of 5 mm., except toward the posterior end where they are about twice as long (fig. 5). At the anterior end there is a band of