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THE PALEONTOLOGY OF MINNESOTA. 
[Bumastus orbicaudatus. 
Bumastus orpicaupatus Billings (sp.), 1859. 
Illenus orbicaudatus BILLINGS, 1859. Canad. Nat., vol. iv, p. 379. 
Illenus orbicaudatus BILLINGS, 1866. Cat. Silur. Foss. Anticosti, p. 27, fig. 10. 
There is a single cranidium from the Galena shales at Wykoff, Minnesota (Dr. 
Robbins’ collection), which appears to represent this species, described originally 
from the Trenton or Hudson River horizon at English Head and elsewhere, Anticosti. 
Fig. 36.—Bumastus orbicaudatus Billings. Galena shales, Kenyon. 
Bumastus orbicaudatus and B. trentonensis resemble each other in many respects, 
though specimens of the latter are of decidedly smaller size and greater convexity of 
cephalon. The Wykoff specimen measures 20 mm. in length, and 26 mm. in width 
across the base. Certain large, smooth, unsegmented pygidia from the Galena 
shales at Kenyon are probably parts of the same species. 
Genus BATHYURUS, Billings, 1859. 
Batuyurus ExtTans Hall, (sp.), 1847. 
Asaphus? extans HALL, 1847. Palxontology of New York, vol. i, p. 228, pl. 60, figs. 2a-c. 
Asaphus extans HALL, 1850. Third Ann. Report N. Y. State Cab. Nat. Hist., p. 174, pl. 3, figs. la-c. 
Bathyurus extans BILLINGs, 1863. Geol. Canada, p. 158, fig. 114. 
cf. B. longispinus WALCOTT, 1876. Twenty-eighth Rept. N. Y. State Mus., p. 94. 
This species was founded on a pygidium from the Birdseye limestone, professor 
Hall’s description of 1847 being supplemented by an account of the cephalon and a 
portion of the thorax, in 1850, Mr. Billings proposed the genus Bathyurus in 1859 
(Canadian Naturalist, vol. iv, p. 364), taking this species as its type and giving, in 
1863, the first figure of the entire test. Mr. Walcott’s B. longispinus, from the Black 
River limestone of Russia, N. Y., and the Trenton horizon at Platteville, Wisconsin, 
appears to me the same species. : 
Fig. 37.—Portion of head of Bathyurus ewtans Hall, Cannon Falls. 
Among the specimens loaned for my study by the late Mr. Scofield, is one of this 
species retaining most of the cephalon and an impression of part of the thorax and 
pygidium, from the lower Trenton or Birdseye horizon at Cannon Falls, Minnesota. 
It is the only example observed which may be safely referred to the species. 
