Page:Proceedings of the United States National Museum, Volume 76.djvu/140

12

A small, poorly preserved example of this peculiar animal was secured from the Kinzers formation in Pennsylvania and placed in Doctor Walcott's collections many years ago. Little can be said about it since its characters are not well shown, but the observation may be made that the appendages, of which there are 12 or 13 pairs, are relatively longer than in any of the described species. The rear segment appears to be rather deeply notched.

Horizon and locality.—Lower Cambrian, Kinzers formation; (loc. 12x) near Rohrerstown, Pennsylvania.

Holotype.—Cat. No. 80487, U.S.N.M.

Only one specimen of this form has been found in the Eager formation. This species has about fourteen or fifteen abdominal segments and blunter appendages than A. pennsylvanica. The caudal segment is much like that figured by Walcott for A. whiteavesi.

This like the preceding specimen is not well preserved so that it is difficult to determine its features. The interesting thing in this connection is the occurrence of these rare animals in such old beds and associated in both cases with Tuzoia.

Horizon and locality.—Lower Cambrian, Eager formation; (loc. 67g) near Cranbrook, British Columbia.

Holotype.—Cat. No. 80479, U.S.N.M.


 * Protocaris, 1884, Bull. U. S. Geol. Surv., No. 10, p. 50.
 * Protocaris,, 1886, Bull. U. S. Geol. Surv., No. 30, p. 147.
 * Protocaris, 1888, Mon. British Pal., Phyllopoda, Pal. Soc., p. 2.

Walcott's drawing of the genotype published in 1884 has been copied many times and much has been written about it. The single carapace of Roddyia described in the following pages brought up the question whether or not it was a Protocaris. It was quite a surprise on looking at that specimen for the first time, to note at once that it had two valves and was almost conspecific with the Burgess shale P. pretiosa. Since hitherto P. marshi was always regarded as an Apus-like form with an undivided carapace, naturally the previous descriptions need revision. Walcott, however, indicated a possible relationship of this primitive crustacean with "the Nebalidae