7 
166 y ` General Notes. ` [February, 
that the fact has been admitted that many of these’ fucoids are in 
reality inorganic. 
Let any one consider for a moment the structure of the most 
of the species of modern Algze; remember how easy it is for 
cellular tissue to be destroyed by only a short immersion in 
water, and the unreasonableness of expecting to find fossil Algz 
will be perceived. Or again, let anyone turn, as Professor Les- 
quereux, for one, has done, to modern sea beaches; let him see 
the immense masses of kelp thrown up by the waves of every 
storm, and see how soon they disappear by passing “ into gelatin- 
ous, half-fluid matter, which penetrates the sand” (Lesq.), and he 
will again see how unreasonable it is to say Algz can be long 
preserved. Even when covered with sand, mud or clay they dis- 
appear and leave no trace behind them. 
' Professor Hall, in the first two volumes of the Paleontology 
of New York, enumerates thirty-six species and varieties of these 
fucoids from the Trenton, Hudson River and Clinton groups. He 
recognizes the fact that many trails, burrows and possible water 
marks are preserved in the rocks, but has no hesitation in refer- 
ring many fossil marks to undoubted Algæ. Later writers have 
not been behind in naming and describing other species. In 
1878 fourteen new ones were added as found in the rocks of the 
Cincinnati group. Recent investigations of these fourteen, and 
of some eighteen others reported from this group, have revealed the 
fact that wot a single one is an undoubted Alge, a// can be referred 
either to water marks, trails, tracks or burrows of different sorts, 
or to graptolites. : 
_ This statement can be proved only by comparison with marks 
found on recent beaches and mud flats. Sir Charles Lyell has 
shown how leaves, impressions of bird tracks, mud cracks, worm 
` 
_ borings and rain-drop impressions can be and are preserved on 
the mud flats of the Bay of Fundy. There is no reason for suppos- 
ing that circumstances were less favorable during the continuance 
of the Silurian epoch in geological time. The writer of this has 
studied many recent mud marks, and has seen in process of for- 
mation tracks and burrows which resemble, to an astonishing 
degree these fossil marks. 
For instance, the burrows made by a species of beetle in the 
mud wonderfully resemble some of the fossils, Paleophycus ru- 
gosus, for example. The trickling of water down a sloping bank 
leaves traces like those which, fossil, have been called Algæ. The 
dashing of rain on the surface of mud leaves marks which have 
been compared to the roots of plants. Impressions left on mud 
by fragments of organisms have been described as fossil Algæ, 
even when not the remotest resemblance could be noted between 
them and any modern prototype.  —Ss_ 
Professor Nathorst, in a memoir written in Swedish! and pub- 
` lOm spar af nagra Evertebrerade rade djur M. M. ochderas Paleontologsika Betydelse. 
