DEVONIAN AGE. 



257 



stone, while empty in other layers. At Terre Haute, Indiana, a well 1,900 feet deep, 

 into the Corniferous limestone, yields two barrels of oil a day, and a second well, 1,775 

 feet, but to the same level (the first 150 feet through gravel), 25 barrels. 



II. Life. 



1. Plants. 



Among Seaweeds, the most remarkable is the spirally convoluted 

 Spirophyion cauda-galli, figured on page 255. 



Fig. 484 A. 



-■■■■'...._ g I y ^sss**®!®^ A 



IIicroscopic Organisms in IIornstone. — Figs, a-i, Protophytes; j-n, Spicula of Sponges ; o,p, 

 fragments o." dental apparatus of Gasteropods. 



The hornstone in the Corniferous limestone, as shown by Dr. M. C. 

 White, is full of miscroscopic plants, or protophytes, from l-500th to 

 1 -5000th of an inch in diameter ; and with them are sponge-spicules 

 and teeth of mollusks. Some of them are represented in Fig. 484 A : 

 a to e are Xanthidia, spore-capsules of Desmids (p. 135), f, g, con- 

 ferva-like filaments, made of a series of cells ; i, a Diatom, one of the 

 silica-secreting protophytes ; while j, k, I, m, n represent siliceous 

 spicula of sponges, and o, p, teeth of mollusks. The mass of the horn- 

 stone was probably made out of siliceous diatoms, sponge-spicules, and 

 perhaps also polycystines. 



The terrestial plants are, — first, under the division of Acrogens, or 

 the higher Cryptogams, species of Lycopods (or Ground Pines) and 

 Ferns ; second, under Gymnosperms, or the lower division of Pheno- 

 gams, Conifers. In the lower sandstones of Gaspe occur remains of 

 the Lycopods and Conifers, and in the Corniferous limestone of Ohio, 

 the Ferns. 



1. Lycopods. — The Lycopods include species of Psilophyton, like 

 thosa of the Oriskany period : portions of the plant, with its dried 

 leaves, are shown in Figs. 484 B, a, b, and its fructification in c, d. 



The species differ from the common Ground Pine in having the 

 leaves nearly wanting, on the flowering stems, and also in having the 

 axis, or a cylinder around the centre, made up of scalariform vessels, 

 and the spore-cases (fruit) usually in pairs on short pedicels ; and in 

 these respects they resemble the plants of the genus of Lycopods 

 17 



