72 ROYAL SOCIETY OF CANADA 



accumulated over the muddy la3'er the worm continued to keep the two 

 ends of tlie burrow open and connected with tlie surface by the vertical 

 holes by which it had egress and regress. In this species the holes are 

 not strictly vertical but are inclined toward each other, so that if the sand 

 accumulated to a considerable depth the pits approached each other more 

 and more at the orifice, so that eventually they almost came in contact. 



The rock in which these burrows are made are inclined to split 

 along the shaly layers, because the sand of the flaggy layers is more 

 tirmly cemented than the clay of the shaly layei*s ; in this way surfaces 

 are exposed that are covered with the horizontal galleries of this species. 

 As Arenicolites had the habit of enlarging the ends of the horizontal 

 gallery somewhat, this gallery often assumes the dumbbell appearance to 

 which Mr. Billings alludes. 



Size. — Some of the examples I have collected are larger than those 

 described by Billings ; the}^ average about eleven lines (24 mm.) though 

 some are one and a quarter inches in length (32 mm.). 



Horizon and I/ocalitt/.—'Nesir Lance Cove, Great Bell Island, Con- 

 ception Bay, Newfoundland, in beds referred to the Upper Cambrian, by 

 Messrs. liowley and "Walcott. 



Arenicolites brevis ? 



Arenicolites brevis. Matt,, Trans. Roy, Soc. Can., vol. viii., pt. iv.,p. 159, pi. xi., figs, 



13 a, b and c. 



On the surfaces over which the above burrows are scattered there are 

 smaller ones, which are both narrower and shorter ; the sandstone in 

 which they occur, do not have any burrows sufficiently well exposed 

 to show whether they have short holes leading to the gallery, as in A- 

 brevis, or longer ones, but they are comparable to this species in the size 

 and length of the galleries. 



Size. — Length of the galler}- 11 to 14 mm, ; width 2 mm. 



The length of the vertical holes in this species probably dej)end8 

 upon the thickness of the sandstone bed in which it is found, so that a 

 variation in this respect is not of much importance, 



CTENICHNITES. 

 Ctenichnites ingens ? 



Ctenichnites ingens, Matt., Trans. Roy. Soc. Can., vol. viii., pt. iv., p. 151, pi, liv. 



flgs. 1 to 12 and ? 13 to 15. 



On the surfaces which carry the casts of the galleries of Arenicolites, 

 quite distinct groups of the striae, which compose the above tracks, are 

 found. The slabs collected are too small to show long tracks such as 



