238 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



DESCRIPTION OF PLATE 28 



PAGE 



Norwoodia ponder osa Walcott 171 



Fig. I. (X6.) Matrix of a craiiidium compressed in fine shale. The 

 occipital spine is restored. U. S. National Museum, Cata- 

 logue No. 61612. 

 10. (X 5.) Cranidium varying in form from fig. I. U. S. National 



Museum, Catalogue No. 61613. 

 ih. (X6.) Minute pygidium associated with this species. U. S. 

 National Museum, Catalogue No. 61614. 

 The specimens illustrated by figs, i, la-h are from the Upper 

 Cambrian: (90a) Conasauga shale; Cedar Bluff on Coosa River, 

 Cherokee County, Alabama. 



Norwoodia tenera Walcott 172 



Fig. 2. (X6.) Small cranidium. U. S. National Museum, Catalogue 



No. 61615. 



20. (X6.) Dorsal view of a small dorsal shield with seven 



thoracic segments. U. S. National Museum, Catalogue 



No. 61616. 



26. (X6.) Dorsal shield with eight thoracic segments. U. S. 



National Museum, Catalogue No. 61617. 

 2c. (X8-) Minute cranidium. U. S. National Museum, Cata- 

 logue No. 61618. 

 2d. (X6.) A detached median thoracic spine. U. S. National 



Museum, Catalogue No. 61619. 

 2c. ex 4-^ A broken dorsal shield on which there is a thoracic 

 segment with a median spine attached. U. S. National 

 Museum, Catalogue No. 61620. 

 2/. (X4-) A very minute cranidium beside a larger form. U. S. 



National Museum, Catalogue No. 61621. 

 2g. (X 4-) Side outline of larger cranidium represented by fig. 2/. 

 The specimens illustrated are from locality 3011, Upper Cambrian : 

 Weeks formation, Weeks Canyon, House Range, Millard County, 

 Utah. 



Millardia semele Walcott 166 



Fig. 3. (X4-) Small cranidium showing tuberculated frontal rim. 

 U. S. National Museum, Catalogue No. 61622. 

 2,a. (X4.) Ventral surface of a cephalon. U. S. National Mu- 

 seum, Catalogue No. 61623. 

 Sb. (X4-) Dorsal shield with 23 thoracic segments. U. S. 



National Museum, Catalogue No. 61624. 

 Sb'. (Natural size.) The same specimen as that represented by 



fig. 3b. 

 2c. (X4-) Compressed dorsal shield on surface of shaly lime- 

 stone. U. S. National Museum, Catalogue No. 61625. 

 3c'. (Natural size.) The same specimen as that represented by 

 fig. 3c. 

 The specimens ilkistrated are from locality 30 0, as given above 

 under figs. 2, 2a-g. 



