6 PROCEEDI]SrGS OF THE NATIONAL MUSEUM vol. 76 



Tuzoia when first described was referred to the Leptostraca, and 

 subsequent studies have confirmed this position.^ 



Henriksen (p. 11) suggests that Anomalocaris belongs to the same 

 group and that it may be the body of Tuzoia or Gamarvonia. Wal- 

 cott^ associated several phyllopod carapaces, which have since been 

 referred to Hymenocaris and Isoxys, with Anomalocaris prior to the 

 discovery of the numerous entire specimens of Hy^ienocoHs in the 

 Burgess shale. In support of Henriksen's idea that Anomalocaris 

 may be the body of Tuzaia it may be stated that three of the four 

 localities yielding Tuzoia have thus far also furnished Anomalocaris 

 and that the latter has been found independently only on Mount 

 Stephen. 



Genus TUZOIA Walcott, 1912 



Tuzoia Walcott, 1912, Smithsonian Misc. Coll., vol. 57, no. 6, p. 187. 

 Tuzoia Henbiksen, 1928, Vidensk. Medd. fia Dansk naturh. Foren., vol. 86, 

 p. 16. 



Large j)hyllopod with carapace consisting of two convex valve- 

 like portions. Shell thin, and lateral portions semi-oval, narrowed 

 anteriorly, probably curved evenly downward from the dorsal line; 

 each valve increasing in convexity from the edges toward the keel 

 that extends almost the full length of the shell in an approximately 

 central position; posterior margin usually has several large spines; 

 smaller spines may edge all but the extreme anterior portion of the 

 margin; strong spines along the dorsal line in many species; also 

 on the central keel in some species, sometimes their broad bases unite 

 to form a scalloped frill. Surface usually reticulate; the meshes on 

 the keel and near the dorsal line usually smaller and more crowded 

 than on other parts of the shell. No external eyes or muscle scars 

 observed. 



GonypaHsons. — Comparing Tuzoia with Protocaris we notice that 

 the shape of the valves, their relative size and the presence of a keel 

 make the two forms look much alike. However, Protocaris lacks 

 the reticulations and marginal spines which are persistent features of 

 Tuzoia and thus offers an easily applied means of distinguishing 

 them. If Anomalocaris is actually the abdominal portion of Tuzoia 

 considerable differences of body structure exist. Both specimens of 

 Protocaris thus far obtained retain the soft body, whereas none of 

 the numerous Tuzoia specimens do, which in itself points to a 

 difference of structure. 



Attitude of valves in huHal. — Some of the specimens were en- 

 tombed in such a position that both valves were flattened together 



•Henriksen, Critical Notes upon Some Cambrian Arthropods. Vidensk. Medd. fra 

 Dansk naturli. Foren., vol. 86, 1928, p. 15.' 



'Mount Steplien Rocks and Fossils. Canadian Alpine Journ., vol. 1, no. 2, 1908, p. 2. 



