No. 381.] A HALF-CENTURY OF EVOLUTION. 637 
in calcareous and cherty rocks of “undoubted Precambrian 
age” near Adelaide, Australia (Mature, Dec. 24, 1896, p. 192); 
the detection of fossils in the Archzean of Brittany,and of three 
veins of anthracite “in crystalline schists of Archzean age ” in 
Ecuador. 
At St. John, New Brunswick, that able and experienced 
geologist, Dr. G. F. Matthew, has detected fossils in strata 
which he refers to the Upper Laurentian. They occur in three 
horizons. The lowest series is composed of a quartzite con- 
taining fragments of the skeletons of hexactinellid sponges allied 
to Cyathospongia. In the upper limestone of the second horizon 
were collected calcareous coral-like structures resembling S¢vo- 
matopora rugosa. Inthe third and uppermost horizon, consisting 
of beds of graphite, occurred great numbers of spicules of 
apparently hexactinellid sponges. “ Between this upper Lauren- 
tian system and the basal Cambrian occurs,” says Matthew, “a 
third system, the Coldbrook and Coastal, Huronian, which has 
given conglomerates to the Cambrian and has a great thickness.” 
He also tells us that the Precambrian St. Etcheminian beds at 
St. John, consisting of red and green slates and shales, have a 
meager fauna, comprising Protozoa, Brachiopoda, echinoderms, 
mollusks, with plentiful worm burrows and trails. In com- 
menting on this subject Sir J. W. Dawson remarks that these 
Etcheminian strata rest on Huronian rocks which, near Hastings, 
Ontario, contain worm burrows, sponge spicules, “and laminated 
forms comparable to Cryptozoén and Eozoén.” (Nature, Oct. 
15, 1896, P. 585.) 
Even allowing room for error in the correlation of these 
formations, and in regarding some of these rocks as no older 
than Cambrian, yet on the whole the result appears to be that 
abundant vegetation existed in Precambrian times, which was 
converted into graphite, while representatives of seven classes 
were perhaps already in existence previous to the Cambrian 
period. 
The following lists give a comparative view of the classes of 
the periods in question: 
