134 The American Geologist. September, ism 
Being at that time engaged in a study <«f the Clinton fossils 
of the state. Prof. Orton sent the above communication with 
tin- specimen to the writer, who perceived at once its identity 
witli much more perfect specimens discovered the preceding 
year at the same quarry. One of these, while presenting 
similar exterior markings, showed by its interior structure 
th.it these fossils belong to some curved or coiled type of 
nautiloid cephalopods, like Cyrtoceras or Gyroceras. The 
exterior markings, however, being indistinct in all the speci- 
mens, they were supposed to be due to a concretionary layer 
of lime surrounding the original fossil. When, in Vol. 7. 1888, 
of the Paleontology of New York, C. E. Heecher published 
Cyrtoceras subcompressum from the same quarry, the identity 
of all of these Brown's quarry specimens was recognized : 
and in a paper read before the Boston Society of Natural 
History. May 1, 1889, and published in its proceedings, the 
writer gave a figure showing the interior structure of one of 
his specimens, a too distinct figure of some of its surface 
markings, and a conjectural figure showing the supposed de- 
gree of coiling. This last is now believed to be entirely 
incorrect. 
The writer suspected that the Glyptodendron eatonensi of 
( laypole might eventually prove to belong to the same species, 
and in 1890 he made a trip to Akron, Ohio, to see the type 
specimen. The surface markings of the latter were much 
larger and to a certain degree different in form from those of 
the Brown's quarry specimens. In 1892 the writer discovered 
at Huffman's quarry, southeast of the asylum at Dayton, a 
specimen which threw new light upon the matter, and a second 
trip was taken to Akron to secure a better knowledge of the 
Eaton Glyptodendron, and it then became evident that the 
various fossils here discussed were at least of the same type. 
The Eaton Glyptodendron and the Brown's quarry Ci/r?<>- 
ceras have been sufficiently described in the publications 
above cited. The Huffman's quarry specimens will be de- 
scribed in the forthcoming volume of the Ohio Geological 
Survey. It remains therefore only in this place to institute a 
comparison between the various specimens and to note the 
conclusions. 
The Brown specimens show the septa and the siphuncle; 
