98 ROYAL SOCIETY OF CANADA 



lar skeletons they were not easily recognized, except in a bright light 

 and on the moistened snrtaces of the shale. In that and subsequent years 

 I undertook detailed collecting in these beds. The thin productive lay- 

 ers being inclosed in ledges of compact shale, much material had to be 

 quarried away in order to obtain access to them, and the work could be 

 carried on only at low tide. The best method of proceeding was found to 

 be to trace the fossiliferous layei-s along the ledges, and having quarried 

 out as large slabs as possible, to convey these to where they could be 

 split \ip and examined at leisure. By pursuing this method sufficient 

 quantities of material could be obtained t(j enable satisfactory compari- 

 sons to be made. The method, in short, was the same which 1 have pur- 

 sued in collecting delicate fossil plants and the smaller animal remains 

 from the Devonian and Coal formation, and which has enabled so many 

 species of delicate vegetable organisms from Gaspé and Nova Scotia to 

 be restored in their external forms. 



The facts observed up to 1889 wei*e detailed in the paper of that 

 date, in ])reparing which I was indebted to Dr. G. J. Hinde, F.E.S., the 

 author of the British Museum Catalogue of fossil sponges, and of so many 

 valuable papers on these organisms, for most important information as to 

 the structure and probable affinities of the species. In addition to the 

 notes of Dr. Hinde given in the previous paper, I am indebted to him for 

 further important suggestions contained in these pages, and for the 

 description of an additional species. 



Since 1889 excavations have been continued iVom time to time, with 

 the view more particularly of discovering new species and of obtaining 

 more ])erfect examples of those previously known. In noticing the results 

 obtained. I shall first refer to certain points relating to mode of occurrence 

 which have been more definitely settled, and shall then present a catalogue 

 of the species, with short descri])tion8 and ligures. 



In regard to tlie figures, I may ex])lain that those in the text are of 

 two kinds: (1) Camera tracings, slightly enlarged, of the spicules, as 

 seen under the microsc()i)e ; (2) Restorations, mostly based on combining 

 several more or less com})lete specimens. Those in the plates are produced 

 from enlarged photographs taken usually from moistened surfaces under 

 a bright light. These were printed and carefully retouched to render 

 them more di.stinct, then reproduced in negatives of or near to the natural 

 size, and copied from these for printing. Those which were sufficiently 

 distinct for this, were reproduced without being touched. 



In the former paper, of 1889, Dr. Hinde ably discussed at some 

 length the state of preservation of the specimens. He remarks that the 

 skeletons of the greater number of the species were made up of delicate 

 spicules, often cruciform, and arranged in such a manner as to form a 

 thin lattice-like framework inclosing a hollow s])ace or sack, and support- 

 ing the soft animal membranes. In the meshes of this framework, and 



