THE KIMMSWICK AND PLATTIN LIMESTONES 
213 
In a similar species (Loxoceras .^)/from the Richmond forma- 
tion at the Clay Cliffs on the eastern shore of Manitoulin Island, 
the vertical color bands are about 1 mm. in width and are sepa- 
rated by intervals varying from 1 to 2 mm. where the diameter 
of the shell equals 15 mm. 
In Orthoceras trusitum Clarke and Ruedemann, from the 
Guelph at Rochester, New York, specimens occasionally show 
color banding. In the specimen represented by figure 2 on 
plate 13 of Memoir 5, New York State Museum, 1903, there are 
9 or 10 vertical light brown bands in a width of 3 mm. In the 
specimen represented by figure 9 the structure usually accom- 
panying color banding is present, but there is no distinctive 
color here. This structure consists in the space between the 
color bands being composed of a less dense and more readily 
weathering material than that forming the color bands. 
In all cases of color banding observed by the writer the color 
banding consisted of various tints of brown. 
30. Spyroceras bilineatum Hall 
In typical Spyroceras bilineatum, from the Trenton of New 
York, the coarser vertical striae alternate with finer ones. 
Conchs of this type occur at the top of the Plattin limestone at 
Conn’s Ford, Buford Cave, and elsewhere in Ralls County. 
They are accompanied by other specimens in which the vertical 
striae practically are of uniform size. In one specimen 17 mm. 
in diameter, these vertical striae number 12 or 13 in a width of 
5 mm. 
31. Tripteroceras cf. planoconvexum Hall 
In the Hormotoma major zone 4^ miles east of Frankford, in 
Pike County, south of the crossing of the pike to Louisiana 
across the western branch of Sugar Creek, a species of Triptero- 
ceras was found which is identical with the species figured by 
Clarke from the Prosser limestone at Hader, Minnesota (Pal. 
Minnesota, III, pt. 2, 1897, pi. 57, fig. 1). Compared with 
typical Tripteroceras planoconvexum, from the vicinity of Beloit, 
Wisconsin, however, the species here under consideration appears 
larger, and with a smaller apical angle. 
