156 Screntific. Intelligence. 
onward to its mouth and, then, nearly three miles wp the Canadian 
cation. How far down this river was not ascertained. 
The enormous extent of the erosion over the plains which pre- 
ceded the time of the eruption of this basalt, the author attributes 
to an era of unusual precipitation that had then n passed by. 
10. On the occurrence of “oa nak gi el Hall ; b 
Wiu.iams. (Communicated.)—Th specimen of this Trilo- 
bite of which aes ieae notice tas “tat taken is, so far as I can 
and 9 
Plate 10. The same otis so, is figured in the “ Tineeatios of 
Devonian Fossils,” 1876, Plate xx, figs. 32-34, and the same 
notice is given of the specimen, so that we take for granted that 
in 1876 Professor Hall had seen only this specimen. The original 
specimen is said to have come from “far northeast of Des Moines, 
and is regarded as from Hamilton rocks by Hall. 
have recently examined two more specimens of the same 
species, one a pygidium about the size of Hall’s specimen, and the 
other a complete and nearly perfect specimen, but only about a 
third as large, folded up, and the pygidium protruding beyond the 
anterior margin of the glabella, asin the original s specimen. They 
agree well with Hall’s s description and figure. The “nine” dorsal 
segments, the “ twenty annulations on the axis of the pygidium,” 
and the other details of the description are well carried out. 
Only about twenty of the annulations on the axis could be counted 
in the larger specimen, but there was still room for two or three 
1 
to count beyond fifteen or sixteen, but the proportion 0 of those 
seen and their relations to the length of the axis leave little 
doubt of the perfect identity of these with the original form as 
The specimens were sent for examination by Edwin Walters, 
Principal of the Madiesn Public Schools, Madison, Kansas. He 
writes that they were found in a blue limestone near Madison, 
found northeast of DesMoines, Iowa, where Carboniferous strata 
crop out, if one does not go too ar into the corner of the State. 
Still, from what we know of the two localities, the Kansas rocks 
are more noe than those of northeastern Iowa 
Mr. ers promises to make further examination, and a few 
ens oa Pit will fix with greater accuracy the horizon of this 
species. It certainly is one of the later ee of its race, 
and may prove to be the last one know 
Cornell University, Ithaca, December, 1880. 
