36 
the Micro-Polariscope, exhibiting a gorgeous display of colors 
when the interposing Selenite film is used. 
Dr. T. A. Tellkampf read a paper on Ascidia Manhattensis, 
describing its anatomy, habits and mode of reproduction in 
detail. This paper is to be published in full in the Annals 
of the Lyceum. 
May 30, 1870. 
The President in the chair. Twenty-four persons present. 
Dr. L. Feuchtwanger exhibited a well-preserved specimen 
of Icthyosaurus tenuirostris nearly three feet in length, from 
the Lias of Wurtemburg. Also a specimen of Dendritic 
Manganese from the Hot springs of Arkansas and a remark- 
able specimen of the same upon the rounded surface of a 
pebble from the bed of the Stanislaus River, California. He 
remarked that he considered that the mode of formation of 
these Dendrites had not been satisfactorily explained as yet ; 
the specimen upon the rounded surface not being explainable 
by the means usually employed. 
Dr. J. S. Newberry called attention to some curious facts 
with regard to the red-colored sedimentary rocks; illustrating 
his remarks with specimens of Potsdam Sandstone from 
Lake Superior and Red Shale of the Onondaga Salt group, 
from near Syracuse. All of these sedimentary deposits, 
which are strongly colored with the Red Oxide of Iron have 
been found to be singularly wanting in fossiliferous remains 
and this is the more remarkable as it can hardly be supposed 
that the seas from. which they were thrown down were so 
destitute of organic life as this fact would lead us to suppose. 
On the specimens exhibited there were circular spots, often 
over an inch in diameter, the prevailing color of which was 
either whitish or greenish, but at the centre was always a 
seeming nucleus of a darker tint. This central spot was 
