Plate 2 



1-3, Pycnaspis sp. indet. USNM 21337 from Middle Ordovician, Winnipeg formation. 

 Shell Pine Unit No. 1 core, depth 9525-9531 feet, sec. 30, T. 12 N., R. 57 E., Wibaux County, 

 Mont.: 1, detached exoskeletal plate, somewhat incomplete, external view; 2, 3, same, lateral 

 views from opposite sides. 



4-8, Eriptychiida gen. and sp. indet. 4-7, USNM 21340, branchio-corimal plate from 

 the same layer and locality as the holotype of Pycnaspis splendens, new genus, new species: 

 4, lateral view; 5, ventrolateral view; 6, posterolateral view; 7, medial view, showing the 

 basal face of the plate after removal of the matrix. 8, USNM 21341, fragment, possibly of 

 another branchio-cornual plate, from the same layer and locality as the foregoing; a short 

 wide canal in the interior (.f the plate, which may be a lateral line canal, is shown on the 

 broken-off surface. 



Magnification: 1-3, X 12; 4—7, X 2.4; 8, X 4. Explanation of symbols: Z^r. o, branchial 

 opening; llct, possibly a lateral line canal. 



