16 PEOCEEDINGS OF THE jSTATIONAL MUSEUM VOL.76 



Plate 3 



Page 



Tuzoia burgessensis, new species 8 



Fig. 1. A large left valve. Keel pressed directly downward. Folding to 



accommodate this reduction in convexity resulted in a crowded 



zone about half way to the margins. Paratype, Cat. No. 80477, 



U.S.N.M. 



Middle Cambrian, Burgess shale; (loc. 35k), near Field, 

 British Columbia. 

 Tuzoia manchuriensis, Resser and Endo MSS 9 



2. Upper anterior quadrant of left valve. Note long extension of 



dorsal line and narrowed keel. Paratype, Cat. No. 80481, 

 U.S.N.M. 



3. Major portion of left valve. Reticulations on keel and general 



surface partially visible. Note worm borings. Holotype, 

 Cat. No. 80482, U.S.N.M. 



Middle Cambrian, Matrix; soft yellow shale. Fig. 2, from 

 Huo-lien-chai, and fig. 3, from Mount Tang-shih-ling, near 

 Yen-tai, Manchuria. 



Plate 4 



Profocaris pretiosa, new species 13 



FiQ. 1. Abdominal portion of body and both valves of this interesting 

 form. Right valve extended and practically undistorted. 

 Left valve which rests at an oblique angle to the bedding plane 

 crushed down and thereby extended rearward. 



2. Counterpart of same specimen as figure 1, with shell removed to 



expose most of the body. Note the numerous segments and 

 the bifurcated caudal extremity. Holotype, Cat. No. 80483, 

 U.S.N.M. 



Middle Cambrian, Burgess shale; (loc. 35k) near Field, 

 British Columbia. 

 Tuzoia relifera, Walcott 7 



3. Major portion of a poorly preserved specimen referred to the 



species with some doubt, in which the two valves became flat- 

 tened out on the same plane. In this case the original con- 

 vexity of each valve was reduced by overthrust faulting along 

 the keel, together with parallel folding in other areas thus 

 almost effacing the reticulations. Plesiotype, Cat. No. 80484, 

 U.S.N.M. 



Middle Cambrian, Burgess shale; (loc. 35k) near Field, 

 British Columbia. 



Plate 5 



Tuzoia polleni, new species 



Fig. 1. Large right valve in which the spines and reticulations are well 

 preserved. Holotype, Cat. No. 80485, U.S.N.M. 

 2. Small right valve from which the marginal spines have mostly 

 been broken away. Note the numerous small and embryonic 

 specimens of a Mesonacid showing on and through the thin 

 shell. Paratype, Cat. No, 80485, U.S.N.M. 



