196 Views on Prenehular Conditions. — A. Winchell. 
than is usually the case. In all other respects the characters 
appear to agree very well with those of McCoy's genus. 
In America there are probably about a dozen valid species 
of Natlco2)sis, the others described as such being identical 
with forms previously known. Natica littonana Hall from 
the Warsaw limestone apparently belongs to the globose group 
of Soleniscics and therefore will stand as S. littonanus. Iso- 
nema depressa M. & W. as finally written by Meek himself, 
Naticopsis {Isonema) depressa, was preoccupied by Winchell 
for a Kinderhook form ; and it is proposed to substitute the 
name Naticopsis linearis. 
VIEWS ON PRENEBULAR CONDITIONS. 
By Alexander Winchell. 
Geologists interested in the speculative departments of their 
science will be gratified to know the state of opinion concern- 
ing the earliest condition of terrestrial matter on which de- 
ductive reasoning sheds any light. That the matter of our 
planet, in common with that of the Solar System has under- 
gone a physical evolution of the nature first outlined by Kant, 
in 1755, is now almost universally believed by those who have 
based their opinions on a rational examination of the eviden- 
ces. In addition to the familiar proofs, we may mention the 
new and original elucidations of M. Roche, so highly esteemed 
by professor Darwin, and the very remarkable photograph of 
the planetary nebula in Andromeda exhibited to the Royal 
Astronomical Society, on December 6, 1888. This is regard- 
ed by professor G. H. Darwin as affording "something like a 
proof of the substantial truth of the nebular hypothesis.'" 
With reference to the same photograph Dr. Huggins remarks, 
"The stage of evolution which the nebula in Andromeda repre- 
sents is no longer a matter of hypothesis. The splendid 
photograph recently taken by Mr. Roberts- of ftie nebula, 
shows a planetary system at a somewhat advanced stage of 
evolution ; already several planets have been thrown off', and 
the central gaseous mass has condensed to a moderate size as 
'Darwin, Phil. Trans. Nov. 15, 1888. Note added Dec. 19, 1888. An 
excellent engraving from this photograph was published in Knowledge, 
Feb. 1, 1889, and another on a larger scale Aug. 1889. Both reveal an 
annulated structure in the accompanying smaller nebula? (Added Sep. 
7, 1889. 
^Monthly Notices, Royal Astronomical Society. 
