Professor Bonney — Specimens from the Canadian Rookies. 291 



the others may be produced by an animal of the same group, unless 

 they are a peculiar duplication of curving burrows. The underside 

 of the slabs show some ill-marked burrows, and usually the ' glazed ' 

 surface already mentioned. 



(4) A rather rhomboidal slab of greenish-grey quartzite about 

 3" by 2" by 1" with a brownish glaze on one surface. On this are 

 little lumps about the size of a small pin's head, four elongated, 

 rudely parallel, slightly curving elevations, somewhat resembling 

 those mentioned above, but barely tapering and so more spine-like; 

 possibly forming part of the same set are three others, which, 

 however, are less regular in shape. On another part of the slab 

 is a single elevation about as thick as a straw, which may be 

 a burrow, and two or three near scarcely thicker than stout pins 

 (once or twice they are in intaglio). Four of these can be detected 

 underlying the first set and crossing them at an angle of about 60°. 

 These are more like burrows, but if so the tendency to be parallel is 

 perplexing. The material of this specimen is more like that of the 

 next one (5), which is a slab rather rhomboidal in outline, measuring 

 about 11" by 5", and roughly 1^" thick (Plate XVII, Fig. 3). From 

 one surface rise a number (about forty) of bosses, dome-like in form, 

 varying in diameter from about -9" to 1*1", not quite hemispherical, 

 owing to a very slight flattening of the upper part of the dome. 

 A faint ring-like marking, produced occasionally by a slight increase 

 of the radius, but also by a similar decrease, is often perceptible. 

 The majority have a slight depression or dimple at the top (occa- 

 sionally well-marked), as if made by pressure of a blunt- pointed 

 instrument. In one or two cases the outline of the surface seems 

 traceable into the slab for a short distance. These domes occasionally 

 touch one another, once or twice being very slightly flattened at 

 contact. On the slab also are a few worm-burrows, like those 

 described above, a couple of which seem to end abruptly against 

 the exterior of a dome, about as many pass now and then obliquely 

 over the lower part, and one across the top, where it makes a slight 

 depression. All the domes and burrows are coate.l by a filmy 

 brownish glaze. The opposite side of the slab consists of a greenish 

 grey, rather flinty argillite, on which at one place is a flattened, 

 slightly raised swelling, about an inch each way, something like 

 a bag in shape, and of slightly different texture. This argillite, in 

 about J" or ^", passes rapidly into a ferruginous quartzite of which 

 also the mounds consist, but they, together with the burrows, are 

 apparently surrounded by an irregular thin layer of argillite re- 

 sembling that on the other side.^ Besides this slab Professor Collie 



1 By the kindness of Dr. Henry "Woodward I have examined the very interesting 

 collection of rock ' freaks ' (if such a term be permitted) at the British Museum, 

 but it failed to throw light on these singular structures. They present a certain 

 resemblance to some of the peculiar globular concretions in the maguesian Limestone 

 of Durham, which occasionally rise in flattened hemidomes, with a similar sKght 

 restriction of the diameter in a horizontal section. But the dents common at the top 

 of the Canadian specimens are wanting, and the latter shoAV no sign of a concretionary 

 structure, which is rare in a sandstone, and so far as I am aware unknown in 

 a quartzite. I find nothing like them in Nathorst's work (Kong. Svenska. Vetenskaps- 

 Akad. Handliugar, xviii, 18S1, No. 7), nor in Delgado's Etudes sur les BUohites, etc. 



