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II.—New Palæoniscidæ from the English Coal-measures

Published online by Cambridge University Press:  01 May 2009

Extract

Length, 6 to 7 inches, shape fusiform. Cranial roof bones sculptured with undulating ridges passing at times into elongated tubercles. Mandible sculptured externally with slightly undulating longitudinal ridges, which run tolerably parallel with the upper and lower margins of the jaw; dentary margin finely tuberculated. Maxilla of the usual form, its dentary margin likewise finely tuberculated, the rest of the surface covered with undulating ridges. Scales of moderate size; those of the front of the flank are higher than broad; posteriorly they become more oblique and equilateral, while towards the dorsal and ventral margins they become rather lower than they are broad. Their ornament consists of sharp stronglymarked ridges, nearly straight and parallel, and only occasionally bifurcating or intercalated. On the scales of the anterior part of the flank these ridges run rather diagonally over the surface of the scale from above downwards and backwards, but over the greater part of the body they are parallel with the upper and lower margins of the scale, and seldom does any greater obliquity of the ridges in the anterior and lower part of the scale give any indication of the diagonal division of the pattern which is so common in striated scales in the family Palæoniscidfe. Posteriorly, a peculiar and highlyornamental character is given to the squamation by the fact that the lowermost ridge, uniting or not with the one next above it, is of unusual breadth, and stands prominently out.

Type
Original Articles
Copyright
Copyright © Cambridge University Press 1886

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