602 



SIR J. W. DAWSON ON BURROWS AND TRACKS OP 



stems of the coniferous genus Bracliyphyllum ; but Zeiller has re- 

 cently described a roofed tunnel or burrow made by the mole- 

 cricket, which completely reproduces some of the forms known under 

 the name Plujmatoderma.^ I have in my collection (fig. 6) a 



Fig. 6. — Roofed Burrow : Phymatoderma. Silurian ; Ontario, 

 Canada. (From a Photograph.) 



specimen, collected by Col. Grant in the Clinton formation, which 

 shows that some Silurian animal, possibly a Crustacean, made 

 covered burrows of this kind. 



§ III. ScoLiTHus, &c. (Figs. 7 to 10.) 



This genus, proposed by Haldimand as early as 1840, though the 

 name would indicate that it refers to a worm, was originally j^laced 

 with Fucoids ; and both Hail and Billings regarded the cylindrical 

 cavities, designated by the title, as representing '' stems." JS^o evi- 

 dence, however, has been found of any organic matter in connection 

 with Scolithus ; the tubes being usually filled with a sandy argilla- 

 ceous or calcareous material, which weathers out of the hard matrix, 

 leaving cylindrical holes. 



* Bull. Soc. g6ol. France, ser. 3, vol. xii. 1884, pp. 676-G80. 



