1895.] The First Fauna of the Earth. 981 
shown one of the species of annelids. The soft bodies of these 
animals have, of course, decayed, and all that remains to tell 
of their former existence is a vast variety of trails and bur- 
rows, which, in some places, cover the rocks in myriads. ‘The 
problematic character of fossils has caused them to be de- 
scribed as Algæ, but there seems no reason to doubt that they 
were really worm casts, burrows or trails. In Figure 10 are 
shown some species of Hyolithes, a genus of Pteropods now en- 
tirely extinct, but represented in the Lower Cambrian by eight 
species and one variety. Figure 11 is a representation of a 
Fig. 6. Various species of Brachiopoda. 
