DESCRIPTION OF PLATE 24. 



Redlichia chinensis Walcott [see plate 7, figs. 11, iia-r] (p. 104). 



1. X 2. Nearly entire dorsal shield from near Yunnan-Fu, Yunnan, China. U. S. Nat. Mus., Cat. No 



58792. 



lu. X 2. Posterior portion of thorax and pygidium associated in the same bed with the specimen 

 represented by fig. i. U. S. Nat. Mus., Cat. No. 58793. 



In a letter received from Dr. H. Mansuy since the text of this memoir was put in type he states that 

 he had found a specimen of Redlichia chincnsis on which the posterior five segments of the thorax 

 have a well-marked, strong median spine comparable to that upon the corresponding parts of 

 Elliplocepliala asaphoitles Emmons.* 



Zacanthoides typicalis Walcott. 



2. X 1.5. Dorsal view of type specimen from Locality 31, Lower Cambrian, Pioehe shale, Pioche, Lincoln 



County, Nevada. U. S. Nat. Mus., Cat. No. 15454. 



Zacanthoides idahoensis Walcott. 



3. X 1.5. Thoracic segment of Zacanthoides idahoensis Walcott with a long median spine. Locality 



55c, Middle Cambrian, Spence shale, 5 miles (8km.) west-southwest of Liberty, Idaho. U. S. 

 Nat. Mus., Cat. No. 53438. 



Protolenus elegans Matthew. 



4 and 40. Cranidium, natural size and enlarged, X 2. U. S. Nat. Mus., Cat. No. 58794. 



5. Flattened cranidium, natural size. U. S. Nat. Mus., Cat. No. 58795. 



6. Free cheek associated with specimen represented by figs. 3 and 30. U. S. Nat. Mus., Cat. No. 58796. 



7. Enlargement of frontal limb of cranidium, X 7, to show the irregular, radiating raised ridges. U.S. 



Nat. Mus., Cat. No. 58797. 



The specimens illustrated by figs. 4 107 are from the type locality of the genus (Middle Cambrian) on 

 Hanford Brook, St. John County, New Brunswick. 



'Smithsonian Misc. Coll., vol. 53, No. 6, p. 269, pi. 24, figs, i, 9. 



276 



