Page:Walcott Cambrian Geology and Paleontology II.djvu/191

NO. 5 Geographic distribution.—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.

Generic name derived from Pollinger, name of mountain of President range, British Columbia, Canada.

This is a much larger form than Wiwaxia corrugata. One specimen that has the anterior end broken off measures 12 cm. in length, with a width midway of 7 cm. Individual scales vary in length from 10 to 15 mm. The scales are thin, smooth, elongate, and variable in outline as shown by figs. 7-9. They occur in great numbers scattered on the surface of partings of the shale, but in only one example are they grouped together to indicate the size and form of the dorsal surface. Nothing is known of the body of the annelid.

One of the curious facts connected with the scales is that a considerable proportion of them have been traversed by a minute annelid, the trail of which curves and coils about within the area of the scale. This indicates that there was some animal matter attached to the scale which the minute annelid was seeking.

The scales of this species are so radically different from those of Wiwaxia that they do not fall within that genus. There are no dorsal spines so far as known.

The presence of two or three other species of annelids is shown by the presence of scales that vary materially from those of Pollingeria grandis and Wiwaxia corrugata.

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.

As this genus has but one known species the description of the latter will sufficiently define the genus.

Genotype.—Worthenella cambria, 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.