The Cambrian fauna is of extraordinary interest, because it is the most ancient that we know with any fulness, though, of course, it does not represent the beginnings of life. Almost all the great types of invertebrates are already present and very definitely characterized, indicating that life had been differentiating for a vast period before the lowest Cambrian rocks had been laid down. As compared with the faunas of other Palaeozoic periods, that of the Cambrian is very scanty, but our knowledge of it has been greatly increased of late and may be expected to increase in the future.

Though the successive Cambrian faunas have a very uniform distribution over wide areas, there are already indications of local differences which mark out faunal provinces; thus, the Lower and Middle Cambrian fossils of Newfoundland are more similar to those of Europe than to those of the Appalachian and interior regions of America. A fauna of similar date but different facies occurs in Alabama, and farther north in the Appalachians.

Plate I. - Cambrian Fossils.

Fig. i, Orbulina universa Lam., X 12, L. C. 2, Globigerina cambrica Matthew, x 5, L. C. 3, Leptotnitus zitteli Walcott, x 1/2, L. C. 4, Spicule of Protospongia, x 1/2, L. C. 5, Climacograptus emmonsi Wale, x 1/2, L. C. 6, Dictyonema flabelliforme Eichwald, x 1/2, U. C. 7, Archeeocyathellus rensselaricus Ford, x 1/2, L. C. 8, Archceocyathus profundus Billings, x 1/2 L. C. 9, Eocystttes longidactylus Wale, M. C. 10, Lingulepis pinnifortnis Owen, x 1, U. C. 11, Linarssonia taconica Walc.,x 4, L. C. 12, Kutorgina cingulata Billings, x 1/2, L. C. 13, Protorthis billingsi Hartt, x 1, M. C. 14, Camer-ella antiquata Bill., x 1, L. C. 15, Fordilla troyensis Barrande, x 5/2 L C. 16, Rhaphi-stoma attleborensis S. and F. x 5/2. 17, Stenotheca rugosa Hall, x 2, L. C. 18, Hyoli-thes princeps Bill., x 1/2, L. C.

Of Plants nothing is surely known; certain marks on the bedding-planes of strata have been regarded as seaweeds, but they are too obscure for determination, and many are worm tracks.

The fauna is principally made up of Brachiopods and Trilo-bites, but many other types are represented also.

Foraminifera

Foraminifera very like those of the modern seas (Plate I, Figs,I, 2) are found even in the Lower Cambrian.

Spongida

Siliceous Sponges are not uncommon.