154 



('. ]). WALCOTT — DISCOVERY OF SILURIAN VERTEBRATES. 



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examination of the collection 

 obtained by Mr. Stanton proved 

 the presence of the Trenton 

 fauna in the limestone series 

 above the sandstones. When 

 examining a small fragment of 

 sandstone upon which some 

 lamellibranch shells occurred I 

 discovered upon the lower side 

 what appeared to be fragments 

 of placoderm fish plates. Mr. 

 Stanton was then requested to 

 make a larger collection from 

 the sandstone and to carefully 

 review the stratigraphy of the 

 section. This he did, and from 

 his stratigraphic sections it was 

 evident that the fish remains 

 occurred beneath an inverte- 

 brate fauna having a Trenton 

 fades, and an examination of 

 the material disclosed the pres- 

 ence of a large number of plates 

 of placoderm fishes of the types 

 of those of the lower Devonian 

 fauna. 



Owing to the great interest of 

 the discovery, and in order to 

 make myself fully acquainted 

 with the succession of the strata 

 and mode of occurrence of the 

 faunas before it was announced. 

 I went to Canyon City in De- 

 cember, 1890, and studied the 

 section in detail and collected 

 largely from the lower sand- 

 stone and the immediately 

 superjacent limestone. Mr. 

 Stanton's stratigraphic sections 

 were verified, and the debris 

 was cleared away at critical 

 points so as to photograph the 



