604 



SIR J. W. DAWSON ON BUEROWS AND TRACKS OP 



similar to those ejected by many modern worms from their burrows. 

 From these the tubes of Scolithns descend into the sandstone in the 

 manner represented in fig. 8. It is, T think, quite evident that this 

 variety of Scolithu^ represents burrows with castings at their en- 

 trances; and, since it is referable to Sc. canadensis, I have no 

 hesitation in affirming that this interesting specimen indicates that 



Fig. 8. 



-Sectional view of Scolithus, showing castings at the orifices. 

 Perth, Ontario. 



that species at least must be regarded as a worm-burrow. From the 

 forms of these burrows it is not improbable that they may have been 

 lined with a fine membrane sufficient to protect the body of the 

 animal from the roughness of the sand, and that this lining may 

 have aided in preserving their forms. 



It is to be observed with reference to burrows of this kind, that 

 under different circumstances their orifices may present very dif- 

 ferent appearances. Where the castings from them have been removed 

 by a rapid current, they may have merely a simple opening at the 

 summit. Where the animal has moved inward and outward, en- 

 larging the opening, they may be funnel-shaped at top, like the 

 burrows to which the term Monocraterion (Torell) has been applied ; 

 and, where the worm has made grooves radiating from the orifice, 

 forms similar to Scotolithus mirahilis of Linnarsson *, or the forms 

 which have been named Pyrophyllltes and Asterophycus, may have 

 been produced. I do not maintain that the forms indicated by the 

 above names are identical with Scolithus canadensis, but I have seen 

 in connection with that species appearances resembling these forms. 

 Fig. 9 shows a form of this kind ; but it is from a higher horizon, the 

 Clinton, from which formation I have also funnel-topped burrows, 

 like those of the Cambrian Monocraterion. 



The singular radiating markings, from the Cambrian of Nova 

 Scotia, which I have described as Astropolithon Nindii, and which 

 * Trans. R. Swed. Acad. Sci. \ol. ix. 1871, p. 18, pi. v. figs. 21, 22. 



