234 THE CAMBRIAN Tbull.81 



to the Potsdam formation of the Black Hiils of Dakota. 1 In the final re- 

 port, which appeared in 1880, the species described in the preliminary 

 report are illustrated, and descriptions and illustrations given of Palce- 

 ophycus sp. undet., Arenocolites sp. undet. (p. 333), Lingulepis pinna- 

 formis (p. 331), Lingulepis ddkotentis (p. 337), Obolus f pectenoides (p. 

 338), Obolella polita (p. 339), Obolella nana (p. 340). In the preliminary 

 remarks to the paper it is stated that the horizon of the Potsdam forma- 

 tion of the Black Hills appears to be, so far as the fossils will serve to 

 determine, about the same as that of 'Wisconsin and the neighboring 

 States. 2 



The only fossils of the Cambrian fauna identified in Colorado are a 

 species of Dikelocephalus from Quandary Peak of the Mosquito Range, 3 

 and the Lingulepis found in the Trout Creek section (p. 62). 



In 1890 Mr. C. D. Walcott 4 described three species from the Upper 

 Cambrian of the Black Hills of Dakota. They were Ryolithes newtoni 

 (p. 270), Ptychoparia vacuna (p. 275), and P. (Liostracus) panope (p. 275). 



TEXAS. 



The first notice of the presence of a fauna in Texas subsequently 

 assigned to the Cambrian is by Dr. Roemer in 1849. A description of 

 Idngula acutangula (p. 420) and Pterocephalia sanctisabw (p. 421) is given 

 by him in that year without illustrations. 5 



In his more extended work on the geology of central Texas he de- 

 scribes and illustrates Lingula acutangula (p. 90), Pterocephalia sancti- 

 saba? (pp. 92, 93), and the genus Pterocephalia (p. 93). He also illus- 

 trates the head of a trilobite, allied to Arionellus, and the pygidium of 

 another species, on Table xi. 6 



The primordial character of the fauna referred to the Silurian by Dr. 

 Roemer was announced by M. J. Barraude the following year. He 

 compared it with the fauna of the Potsdam sandstone of New York and 

 Wisconsin. 7 



As geologist of the State of Texas, Dr. B. F. Shumard described in 

 18G1, the strata referred to the Potsdam sandstone. Of the fossils col- 

 lected he describes as new; 



Agnostus coloradoensis, p. 218. 

 Arionellus (Bathyurus) texanus, p. 218. 



planus, p. 219. 



1 Preliminary report on the Paleontology of the Black Hills. U. S. Geol. and Geog. Snrv. of the Rocky 

 Mountain region, 1877, pp. 7-11. 



2 Paleontology of the Black Hills of Dakota. Report on the geology and resources of th« Black Hills 

 of Dakota, 1880, pp. 329-344. 



3 Geology and Mining Industry of Leadville, Colorado. U. S. Geol. Surv., Monograph vol. 12, pt. 1, 

 1886, p. (30. 



4 Description of new forms of Upper Cambrian fossils. U. S. Nat. Mus. Proa, vol, 13, 1890, pp. 267- 

 279. 



6 Texas. Mit besonderer Riicksicht auf deutsche Auswanderung und die physischen Verhaltnisse 

 des Landes nach eigener Beobachtung geschildert. Bonn, 1849, pp. 420-421. 



6 Die Kreidebilduugen von Texas und ihre organischen Einschlusse. Bonn, 1852. 



7 (Silur-Gebilde in Texas und am Oberen See.) Neues Jabrbuch fur Miner, 1853, pp.446, 447. 



