ee TT a) eee aN 
C. M. Wetherill on Itacolumite. 61 
former classification, but with a change of names, I declined to 
adopt it. In all the publications of our Survey, in which species 
of this group are described or figured, Athyris is used instead of 
ertstella. 
On the merits of this classification, a note in this Jour., I, 
Xxxill, 130, expresses the views advocated herein. The f ollo ow- 
ing is an extract therefrom 
“This is the classification which ge writer of the criticism maintains 
should be sustained, and we cannot any reasonable objection to it. 
itis perfectly just toward both McCoy and D’Orbigny. It inflicts no 
injustice on any other author. It is not inconsistent with purity of zo- 
ological nomenclature, or in any way injurious to science. It does not 
require any modification in either of the original definitions. The typi- 
eal species are central and dominant forms of two different groups of spe- 
arrangement, is the generic name of that group which has A. tumida 
for its type. Sypirigera is a perry unexceptionable name for the other 
group, of shih the typical form is S. concentrica. Prof. Hall’s pro- 
ART. VIL.—Eaperiments on Itacolumite, (Articulite), with the ex- 
Planation of its flexibility and its relation to the iD. | of the 
mond ; by CHARLES M. WETHERILL, Ph. .D., Profes- 
sor of teen: in the Lehigh University. 
even who are most familiar w ‘it 
According to the authors itacolumite is a laminated quart 
Tock of the talcose series, owing its lamination to a little tale or 
mica, (Dana), to which sandersal its ga is. also due Dan 
a 
