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 1S73, 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 ("vSiliceous 

 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 which 

 wear out rapidly under the influence of cultivation, and its out- 

 crop is found to mark a poor strip of country between areas thaf: 

 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 waiter. The new varieties 

 differ from the parent plant in the color of the sepals and sta- 

 mens. The flowers of one variety are wdiite, 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 l)lue variety had not 

 been observed heretofore. Commelina nudiflora ])roduces 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 eff'ort 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. 



