448 
The Ohio Naturalist. 
[Vol. VI, No. 3, 
grouped in with this division of the Ordovician as its basal 
member. 
Eden is accepted from Orton’s Report on the Lower Silurian 
published in Vol. I of the Ohio Geological Survey 1873, as the 
name for the 250 feet of shale series which surmounts the Win- 
chester. Southward it is found to be thinner, aggregating per- 
haps 200 feet and with a well prounonced sandstone (“Siliceous 
Mudstone’’ of the older Kentucky Survey Reports) in the upper 
part. The name Garrard is retained from the Richmond Folio 
for this portion, and Million, a name proposed by Foerste, is 
accepted for the remainder. The Eden is found to be a very 
widespread formation in Central Kentucky, with its outcrop 
everywhere marked by the same topographic features. It dis- 
stecs into very steep slopes, which, under the influence of culti- 
vation soon wash bare of soil. 
As regards economic features: The Highbridge yields excel- 
lent building stones. The Lexington is traversed by lead and zinc 
mineral veins, which have as their most common gangue, barite, 
shows phosphate and furnishes soil which is the “Blue Grass’’ 
par excellence. The Winchester furnishes grazing lands scarcely 
inferior. The Eden, however, is found to furnish soils w’hich 
wear out rapidly under the influence of cultivation, and its out- 
crop is found to mark a poor strip of country between areas that 
are rich. 
A NEW CASE OF MUTATION.* 
Fred. J. Hillig. 
The origin of two varieties of Commelina nudiflora L. by 
mutation has been observed by the writer. The new varieties 
differ from the parent plant in the color of the sepals and sta- 
mens. The flowers of one variety are white, of the other, pur- 
ple, while the color of the parent plant is blue. Minor differences 
have also been observed. The change was sudden and persisted 
through subsequent generations without a single exception. The 
group of individuals from which the mutated forms originated 
comprises about half a million plants and can be traced back for 
12 generations. The white and purple varieties occur in Euro- 
pean gardens, but their origin from the blue variety had not 
been observed heretofore. Commelina nudiflora produces a great 
number of other forms differing from the systematic species in 
many ways, such as size of plant, form of leaf, number of petals, 
etc. No effort has as yet been made to decide whether these 
divergent forms remain constant. Prof. Hugo de Vries in a 
letter to the writer recommended a careful study of this valuable 
material. 
* Presented at the Cincinnati meeting, Ohio St. Acad, of Sci., Dec. 1, 190.5. 
