36 THE CANADIAN NATURALIST. [Yol. X. 



DESCRIPTION OF A NEW SPECIES OF PSAMMODUS 

 FROM THE CARBONIFEROUS ROCKS OF THE 

 ISLAND OF CAPE BRETON. 



By J. F. Whiteaves. 



PsAMMODUs Bretonensis, Sp. Nov. 



Palatal teeth extremely thin, subrhomboidal, a little longer 

 than broad, the two longest sides nearly parallel and almost 

 straight. Of the two shortest sides one is obliquely and shal- 

 lowly concave at the margin, with one of the angles rounded off 

 and the other produced into a short beak : while the opposite 

 side is obliquely convex at the margin, with both of its angles 

 rounded. The upper surface of the beaked angle of each tooth 

 is somewhat elevated, and this elevation extends nearly to the 

 centre, the remaining portion being quite flat. To the naked 

 eye this surface appears glossy and polished, but, when examined 

 under a lens, with a good light, it is seen to be faintly and rather 

 distantly punctured. The teeth appear to have been placed in 

 linear rows, in such a way that the convex margin of the short 

 side of one tooth fits into the concave and beaked opposite margin 

 of the next one. Measuring from the centre of the sides, the 

 length of one of the teeth is three lines, and the breadth two 

 lines and a half. The average thickness of the teeth is about a 

 quarter of a line. 



Locality : East bank of Scott Brook, nine or ten miles north 

 of St. Peters, Cape Breton Island. Collector : Mr. Hugh Fletcher, 

 B. A., of the Geological Survey of Canada. 



The only remains of this species yet obtained are a number 

 of palatal teeth and impressions of palatal teeth, on the surface 

 of a small flat slab of impure limestone. Most of these teeth 

 are detached and isolated, though in one part of the slab there 

 are impressions of four in an unbroken row. 



P. Bretonensis appears to be most nearly allied to a Psammodus 

 from the Joggins, of which a single tooth is represented by 

 figure 54 (on page 109) of the second edition of the " Acadian 

 Geology," unaccompanied by any description or specific name, — 

 but this figure represents a much larger, thicker and more equi- 

 lateral tooth than any of those of the present species. 



Montreal, March 31st., 1881. 



