Page:Walcott Cambrian Geology and Paleontology II.djvu/192

126 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 generic name is given in recognition of the fine work of Prof. A. H. Worthen, formerly State Geologist of Illinois.

Body slender, elongate, and formed of 46 or more segments and a small head. The segments, as flattened in the shale, have a length of about one-half the diameter, which indicates that when uncompressed the diameter and length of each segment were about the same. Each segment has an annular median furrow that serves to divide it into two narrow rings with a groove between them.

The head is not well-preserved, but it appears to be formed of a large posterior segment and one or two anterior segments. A small shiny spot in front suggests an eye. The head appears to have been conical in form and provided with one or more pairs of tentacles and a pair of palps, the latter being represented by the long filament-like organs extending back from the ventral side of the head. The tentacles are represented by short, faint, jointed appendages extending forward from the front of the head.

The anterior 34 segments of the body show on their inner or ventral side, as compressed on the shale, strong parapodia divided into two filamentous branches. The parapodia of the next posterior 8 segments are longer and more compact. This description of the parapodia is subject to revision as the details of structure are not clear.

Enteric canal.—A very narrow dark line that extends close to the ventral or inner margin of the body from the head nearly to the posterior end, may represent a slender enteric canal.

Measurements.—The only specimen in the collection has a length of about 60 mm.

Observations.—Of this species there is only one specimen and its matrix. The characters described are readily seen by reflected light. The presence of small oval and round scale-like objects on the shale suggests that they may have belonged to the annelid and been detached. If so, with our present information Worthenella cambria is considered to represent an annelid belonging to the order Polychæta. It does not appear to fall within the limits of any of the recent families of the order. It may be that in the collections of