ORGANIC DEPENDENCE AND DISEASE 
91 
In tlie later stages of the Devonian they seem less com- 
mon and become increasingly so through the rest of Pal- 
eozoic time. It would appear that the early Devonian was 
the climacteric period of these Sabella-like boring worms. 
In seeking a designation for these tubes and burrows, 
we have noted the fact that they were described by McCoy 
under the name Vioa prisca from a Silurian mollusk. 
Vioa being an existing genus of boring sponges, and as we 
are convinced that such tubes as were indicated by McCoy 
are referable to the worms, a more appropriate name is 
required and we propose to apply to all of them the desig- 
nation Paleosabellci prisca (McCoy) disregarding differ- 
ences in size, which are often obvious, and of curvature, 
which are slight. We give abundant illustration of these 
occurrences and in the explanations to them point out fea- 
tures of special interest. 
Fig. 76. A stromatoporoid coral from the Niagara group (Silurian) of Hamilton, 
Ont., with weathered holes of boring worms or sponges. 
