226 THE CAMBRIAN. [bull. 81. 



ferred to the Cambrian fauna. In this paper, Dr. Winchell points out, 

 or, rather, he claims, that Dikeloeephalus aud Ptychaspis occur at 

 the recognized base of the Potsdam sandstone. 1 



The preliminary notice of the fauna of the Potsdam sandstone of 

 the upper Mississippi Valley read before the Albany Institute in 1862, 

 by Prof. J. Hall, was published with illustrations in 1863, as has been 

 noticed. The original paper appeared in 1867 in the transactions of 

 the Albany Institute. The descriptions are the same as those of the 

 paper of 1863, with the exception of the omission of those of Theca 

 primordialis and Serpulites murchisoni. 



From the material collected by the Wisconsin Geological Survey Prof. 

 R. P. Whitfield described in 1878 under the title of Potsdam sandstone 

 species : 2 



Palseophycus plumosus, p. 50. Ptychaspis striatus, p. 55. 



Triplesia primordialis, p. 51. minuta, p. 55. 



Palseacnioea irvingi, p. 51. Agraulos (Bathyurus?) woosteri, 



Bellerophon antiquatus, p. 52. p. 56. 



Conocephalites calymenoides, p. Arionellus (Agraulos) convexus, 



52. p. 57. 



Crepicephalus onustus, p. 53. Ellipsocephalus curta, p. 58. 



Dikeloeephalus granulosus, Owen, is redefined under Ptychaspis granu- 

 losa, but not the Ptychaspis granulosa of Hall (p. 54). Ptychaspis granu- 

 losa, Hall, is redescribed as P. striata (p. 55). 



In 1879 Prof. T. G. Chamberlin referred to some tracks found on the 

 Potsdam sandstone by Rev. A. A. Young, of New Lisbon, Wisconsin. 

 He named Glimaetichnites youngi and G.fosteri. The material was sub- 

 sequently studied by Mr. J. E. Todd, who published an illustration and 

 description of the species. These tracks or trails are congeneric with 

 Climactichnites wilsoni, described by Logan in 1863, from Perth, Canada. 3 



In 1882 in his final report on the paleontology of Wisconsin, Prof. 

 R. P. Whitfield described from the Potsdam sandstone the following 

 new species: 4 



Holopea sweeti, p. 174. Dikeloeephalus lodensis, p, 188. 



Conocephalites ? quadratus, p. Aglaspis eatoni, p. 192. 



180. Arenicolites woodi, p. 177. 



( Ptychaspis ?) explanatus, p. 



181. 



He also describes and illustrates : 



Paleophycus plumosus Whitf., p. 169. 

 Lingulepispinnaformis, Owen, p. 169. 

 Orthis pepina, Hall, p. 170. 



barabuensis, Winchell, as Leptajua barabuensis, p. 171. 

 Triplesia primordialis Whitl., p. 172. 



1 Op. cit.,p.226. 



8 Preliminary descriptions of new species of fossils from tlio lower geological formations of Wiscon- 

 sin. Gool. Surv. of Wisconsin, Ann. Rop. for 1877, 1878, pp. 50-58. 



3 A description of some fossil tracks from the Potsdam sandstone. Wisconsin Acad. Sci., Trans, 

 vol. 5, 1882, pp. 276-281. 



4 Paleontology (of Wisconsin). Geology of Wisconsin, vol. 4, 1882, pp, 169-193. 



