Page:Proceedings of the United States National Museum, Volume 76.djvu/129



Among the numerous Cambrian fossils that have been accumulating in the United States National Museum during the last 15 years, there are many undescribed species and some of the specimens are remarkable for the preservation of thin tests or of soft body parts. In order to stimulate further search for the rarer fossils, and particularly for preservations of the softer parts of animals or of delicate plant tissues, it is planned to publish more or less related groups of these animals from time to time. Accordingly, in this paper I have assembled a group of species that centers mainly around the previously described genus Tuzoia, but which also includes several unrelated forms that were secured from the same localities as the others. This paper thus adds several new species preserving more than ordinarily thin tests of crustacea and a few with the still softer fleshy parts. Some are from the well known Burgess shale that has already furnished so many interesting animals and plants, but other formations, some of which have not previously been known to yield such fossils, are also represented.

This paper also contains information of interest aside from that naturally attaching to any description of the softer parts of such ancient animals, by presenting certain important stratigraphic facts in addition to further data regarding the geographic distribution and origin of the faunas to which these species belong.

Acknowledgment.—In the preparation of this paper I was kindly assisted by Dr. E. O. Ulrich in the matter of specific determinations as well as by much appreciated general criticism.

The Pennsylvania specimens of Tuzoia all belong to the Getz Collection in the Peabody Museum, Yale University. I was permitted to describe the two species represented, through the extreme kindness of Dr. Carl O. Dunbar, who had previously planned to describe them himself.

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