. The Canadian journal ; a repertory of industry, science, and art ; and a record of the proceedings of the Canadian Institute. Fio 13. Ventral aspect of an imperfect specimen. 14. The left rhomb alone. The rbombs of this beautiful species are lozenge-shaped, witli straight sides and sharp angles. They are much larger than those of Pleurocy stiles squamosus, and situated perpendicularly —that is, the longest diagonal of the rhomb extends up and down, and the shortest lies across the fossil. The reverse of this is the order in which they are disposed in the other two species. In all the species
. The Canadian journal ; a repertory of industry, science, and art ; and a record of the proceedings of the Canadian Institute. Fio 13. Ventral aspect of an imperfect specimen. 14. The left rhomb alone. The rbombs of this beautiful species are lozenge-shaped, witli straight sides and sharp angles. They are much larger than those of Pleurocy stiles squamosus, and situated perpendicularly —that is, the longest diagonal of the rhomb extends up and down, and the shortest lies across the fossil. The reverse of this is the order in which they are disposed in the other two species. In all the species, it should be here observed, the left rhomb above is the largest. Fig. 14 is the left rhomb of a specimen of the size figured in 13. AU the large plates on the dorsal side have strong rounded ridges radiating from the centres to the corners, and smaller ones between them, which cross the lines of division between the plates at right angles from centre to centre. These are again crossed by lines of growth parallel •with the edges, producing a beautiful woven efiect. Hence the specific name. The integument consists of about forty angular plates of various sizes. These characters separate this species from the other in a very marked manner. In one locality there are great numbers of the plates and disjointed columns of this species, and it was there that the specimen Fig. 13 was found. It is separated from the matrix, but although the back exhibits one rhomb and the character of the striation, yet it is otherwise so much distorted that a figure of it would convey but little instruction. I have not been able to ascertain clearly the size o the other two rhombs. Pleurocystites rohustus. Fig. Of tliis species I have only the fragment hero figiu-ed, but it is so widely diiferent from the others, that there can be little doubt of its being distinct. The rhombs are nearly in the shape of a spherical triangle, one side crossing the suture above and one of the angles being upon
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