of the Goniatite Limestone at Rockford, Indiana. 173 
the Black slate, and is exactly equivalent to beds referred by — 
Prof. Hall at Burlington, Iowa, to the Chemung, its whole group 
of fossils including the Goniatites, strike us as being more nearly 
allied to Carboniferous forms than to those of any of the New 
York rocks. 
If we take for instance the three species of Goniatites now 
known from the Rockford bed, we find first that G. Lyont, Meek 
and Worthen, (= G. hyas of Hall,) which Prof. Hall compares 
with G@. Chemungensis, of Vanuxem, differs materially from 
Vanuxem’s figure of that species, in having but two lobes in each 
Septum visible on either side, while G. Chemungensis is figured 
as having five. It bears no near analogy whatever, to any o 
the species figured by Prof. Hall, from the supposed equivalent 
bed in the Marcellus shale of New York. 
Again Goniatites Oweni of Hall,* is much more closely allied 
to G. princeps of Koninck, (a European Carboniferous species) 
than it is 10 any of those yet known from the Marcellus shale, 
or any other rock in New York. It agrees in size and form 
with Koninck’s species, as well as in having constrictions at inter- 
vals left upon its internal cast by the occasional thickening of the 
lip, while it presents but slight differences in the lobes of its septa; 
the most obvious difference being in the length of its dorsal lobe, 
which is more attenuated than in G@. princeps, though even in this 
character, the Rockford specimens vary to some extent. It is 
true G. princeps, as figured by Mr. Koninck, is marked by reg: 
ular costa, while @. Oweni, as we usually see it in the condition 
of worn casts, seems to be smooth. We have, however, seen 
unmistakable traces of similar cost, on some of the Rockford 
Specimens. We are not contending, however, for the absolute 
Specific identity of these forms, but we do maintain that the 
analogy of the Rockford species to G. princeps is much nearer 
and more striking than its relations to any of the Marcellus 
Shale species, ae 
The third species, Goniatites ixion of Hall, while it presents 
but very remote analogy to any of the Marcellus shale species, 
18 scarcely, if at all distinguishable from the Carboniferous 
Species, @. rotatorius, of Koninck,+ with which Mr. Verneuil 
Considered it identical. They may crane belong to different 
Species, yet the minute differences pointed out by Prof. Hall, 
are, we think, not inconsistent with sane identity in a genus 
like this, Every one who has studied the Ammonitide must be 
aware how unsafe it is to base specific distinctions on minute 
differences in the smaller details of the lobes of the — fod 
upon slight differences in the size of the umbilicus. 
* See thirteenth Ann, Report Regents University New York, p. 100. 
+ Animaux Foss,, pl. 51, fig. 1. 
