790 THE PALEONTOLOGY OF MINNESOTA, 
LOrthoceras junceum. 
thin, gently arched, distant from one-fourth to one-twelfth the diameter; siphuncle 
a cylindrical ventral tube; outer chamber very deep.” (Hall, Joc. cit.) 
This species appears to be represented by various imperfect examples of some- 
what smaller size than the New York specimens, but otherwise agreeing with the 
above description and the original figures. 
Formation and locality—Not uncommon in the Trenton limestone at Minneapolis; in the Trenton 
shales at St. Paul, Eyota, Lanesboro and Fountain, and the Galena limestone at Rockdell. Minnesota. 
In the lower blue beds of the Trenton at Mineral Point, Wisconsin, and in the upper buff beds at Rock- 
ton, Illinois. Also common in the Birdseye limestone at Watertown and elsewhere, New York. 
Museum Register, Nos. 721, 4049, 4052, 5045, 5112, 5578, 7927, 8276, 8277, 8278. 
OrtHoceras JuNcEUM J/Tall/, 1847. 
Orthoceras junceum HALL, 1847. Paleontology of New York, vol. i, p. 204, pl. xLvu, figs. 3a-f. 
To this species are referred a few internal casts of small shells, with circular 
cross-section, central sipho, regular and equidistant septa. - The original description 
of the species is as follows: “Slender, terete-cylindrical, tapering very gradually; 
septa thin, distant from one-fourth to one-third the diameter; siphuncle small, 
central, section circular; surface finely striated transversely, but without longitu- 
dinal striz.” 
Formation and locality——In the Trenton shales at Minneapolis and near fountain, Minnesota. In 
the lower blue beds at Janesville, Wisconsin. 
Museum Register, Nos. 716, 8280, 8281, 8282. 
ORTHOCERAS Compare AMPLICAMERATUM Hall, 1847, 
PLATE XLVII, FIG. 19. 
Cf. Orthoceras amplicameratum HAUL, 1847. Palzeontology of New York, vol. i, p. 205, pl. 11, figs. la-g. 
There are a few moderately large fragments of orthoceran casts which present 
an agreement with this species in general aspect and depth of the air-chambers. In 
the original description, based on much more complete examples than are here 
afforded, the species is thus characterized: ‘“Teretely cylindrical, extremely 
elongated, very gradually tapering; outer chamber profound; septa distant about 
one-third the diameter, very conve, siphuncle excentric, small; surface ?; section 
circular.” 
In one of our specimens the external surface appears to have borne fine, equi- 
distant, longitudinal striz. 
Formation and locality.—From near the base of the Galena limestone at Preston, Minnesota; in the 
lower blue beds of the Trenton at Mineral Point, Wisconsin. 
Museum Register, Nos. 8285, 8286, 8287. 
