390 /. A. Mahony — Organic Remains, in Cowdon Valley. 



in. — On the Organic Eemains found in Clay near Crofthead, 

 Eenfrewshire. 



By James A. Mahony, Esq. 



THE number of the Geological Magazine, for September last,^ 

 contained a description, by Mr. James Geikie, of stratified 

 beds of sand and mud intercalated with Boulder-clay, which occur 

 in the Cowdoa valley, near Crofthead. His reference to some con- 

 tained vegetable debris induced me to make an examination of the 

 strata, which has resulted in revealing an abundance of organic 

 remains quite exceptional in such deposits. 



In the stratified beds, which are cut into to the depth of thirteen 

 feet, there are some layers of vegetable matter. Two are specially 

 well marked ; the lower, two inches in thickness, containing numerous 

 stems of mosses, and the upper (lying seven feet higher in the 

 section) ten to twelve inches thick, being that in which the skull of 

 Bos primigenius was found. These layers differed somewhat in the 

 species of the organic remains, as well as in their comparative 

 abundance, though both were rich in the relics of what must have 

 been a varied fauna and flora. The lower two -inch bed was re- 

 markable for the numerous stems of Hypnum tamariscinum which 

 occurred through its entire mass, and the fragments of a soft- shelled 

 Entomostracan — probably a Daphiia, which must have existed in 

 myriads during the deposition of this bed. It also contained many 

 plant-seeds ; fragments of wood, birch and hazel being most frequent; 

 three species of mosses; and eggs of an insect — one of the Ejihemeridce. 



From the upper leaf-bed I obtained some species of Desmids — • 

 these microphytes being quite absent in the lower bed; eleven mosses ; 

 nine Phanerogams ; and in the animal kingdom, representatives of 

 Protozoa, Annelida, Crustacea, and Insecta. The bed was not equally 

 rich in organisms through its whole extent. On separating the 

 layers at some places, only a fragment of a reed-like plant would 

 be visible, while other parts were crowded with mosses and leaves 

 of the Pond- weed. Where the plants existed in greatest plenty, 

 there the animal remains were also most abundant. The larger 

 objects were removed from the surfaces exposed on separating the 

 various laminge, the remaining portion being afterwards macerated 

 in water, when many seeds were found floating on the surface. The 

 residue was then passed through sieves of different sizes — thus 

 yielding an assorted series of remains which were mounted for iden- 

 tification. 



On examining a portion of this leaf -bed under the microscope, I 

 was gratified and surprised at finding the whole field of view crowded 

 with frustules of Diatoms, many of them broken and all free from 

 endochrome. They abounded in the twelve inch leaf-bed, forming, 

 as nearly as I could determine, one fourth of the entire mass. In 

 order to procure them free from extraneous matter, I steeped 2 oz. 

 of the clay in water for a few minutes, then, with frequent stirring, 



1 Geol. Mag., Vol. Y., p. 393, 



