222 THE CAMBRIAN. [bull. 81. 



Wisconsin. 1 The fossils discovered were referred to the genera Asa- 

 phus, Agnostus, Trinucleus, and Triarthrus, but on PI. 7, accompanying 

 the report, there is figured, but not named, the head and pygidium of 

 Bilcelocephalus minnesotensis, and a species of Ptychoparia as now 

 known. 



In a later paper in 1851 on the paleontology of the lowest sandstones 

 of the Northwest he gives the name " Dikello-Cephalon " to a large 

 genus of trilobites obtained in the lower saudstone formation. 2 He also 

 notes the discovery of Lingulas and Orbiculas by himself in 1847 at the 

 Falls of St. Croix, and the discovery of fossils on the Mississippi River 

 between the Falls of St. Anthony and the Wisconsin River, the pres- 

 ence of trilobites in the sandstone 10 miles below Mountain Island, etc. 



One of the first species described from the u Potsdam " sandstone of 

 Wisconsin is Graptolithus hallianus Prout, 1851, from the middle por- 

 tion of the formation at Osceola Mills, near the falls of St. Oroix 

 River. 3 



The occurrence of the Potsdam fauna in the sandstone of northeast- 

 ern Wisconsin is noted by Prof. James Hall in his report to Messrs. 

 Foster and Whitney. 4 He describes and illustrates Lingula prima Con- 

 rad (p. 204), Lingula antiqua Hall (p. 204), and an undetermined species 

 of Dikelocephalus (p. 205). 



We note that Lingula prima was subsequently described by Hall as 

 Obolella polita, and that Lingula antiqua equals Lingulepis acuminata 

 of Conrad and the Lingulepis pinnaformis of Owen. 



From the material collected from the lower sandstones of Wisconsin 

 (the Potsdam sandstone of New York) Dr. Owen described, in 1852, the 

 following genera and species: 5 



Dikelocephalus (n. gen.), p. 573. Lonchocephalus (n. gen.), p. 575. 

 minnesotensis, p. 574. chippewaensis, p. 576. 



pepinensis, p. 574. hamulus, p. 576. 



miniscaensis, p. 574. Crepicephalus (n. gen.), p. 576. 



iowensis, p. 575. Menocephalus (n. gen.), p. 577. 

 granulosus, p. 575. 



In the description of PI. 1 the species Menocephalus minnesotensis is 

 named and figured (Fig. 11); also Crepicephalus f wisconsensis (Fig. 

 13), and on PI. la, Crepicephalus (?) miniscaensis is named and illus- 

 trated (Fig. 14). On PI. lb, the species Lingula pinnaformis is proposed 

 and illustrated (Figs. 4, 6, 8) ; Lingula ampla is figured and named 



1 Report of a geological reconnaissance of the Chippewa land district of Wisconsin; and incident- 

 ally, of a part of Iowa and of the Minnesota Territory. Letter of the Secretary of the Treasury com- 

 municating a report of a geological reconnaissance of the Chippewa land district of Wisconsin (etc), 

 by D. D. Owen. Thirtieth Congress, 1st Sess., Senate Ex. Doc. No. 57, 1848, pp. 13 15. 



2 Am. Assoc. Proc, vol. 5, 1851, p. 171. 



3 Description of a new Graptolite found in the Lower Silurian rocks near the falls of the St. Croir 

 River. Am. Jour. Sci., 2dser., vol. 11, 1851, p. 189. 



4 Description of new or rare species of fossils from the Paleozoic series. Rept. on the geology of the 

 Lake Superior land district, by Foster and Whitney, pt. 2, 1851, pp. 203-231. 



6 Geol. Surv. of Wise, Iowa, and Minn., and, incidentally, of a portion of Nebraska Territory. Phila- 

 delphia, 1852. 



