Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/411

 Fig. 5. Protopteris peregrina, Newberry, impression of stem, one-fourth the natural size : xx, remains of petioles. 5 a, scar, natural size, showing bundles of vessels at base ; 5 b, portion of a vascular bundle, magnified, showing scalariform vessels and cellular tissue; be, scalariform vessel, highly magnified.

Fig. 6. Lower part of stem of the same, with aerial roots, one fourth the natural size. 6 a, one of the roots, natural size.

Fig. 7. Vascular bundle of Rachiopteris, natural size ; 7 a, portion of the same, showing vascular and cellular tissue, with rounded granules in the cells ; 7 b, one of the cells magnified, showing contained granules.

Fig. 8. Noeggerathia gilboensis, one-half the natural size.

Discussion.

Dr. Duncan doubted the desirability of basing generic and specific terms on imperfectly preserved and indistinct specimens, and pointed out the disagreements among botanists that had resulted from so doing. He would prefer calling fossils such as those described " cryptogamous forms from certain strata." He was doubtful also whether the supposed petrified starch was not merely orbicular silex.

The Chairman (Prof. Morris) remarked on the four different conditions exhibited by existing tree ferns : — first, with roots running down the stem ; secondly, the lower portion with oval scars ; these are, thirdly, further up the stem, rhomboidal vertically ; and, fourthly, higher up still, rhomboidal horizontally ; so that were the plant fossil, distinct genera and species might be founded upon the different parts.

April 5, 1871.

The following communications were read : —

1. On a new Chimaeroid Fish from the Lias of Lyme Regis (Ischyodus orthorhinus, o˞ ). By Sir Philip Grey Egerton, Bart., M.P., F.R.S., F.G.S.

[Plate XIII.]

The knowledge we have hitherto obtained of the form and structure of the fossil fishes assigned to the Chimaeroid family is very limited, being derived solely from the dental plates and dorsal spines, which, from their superior hardness, have resisted the decomposition which has removed the more destructible cartilaginous structures with which they were associated. "Whether these old monsters resembled the surviving members of the family in quaint form and bizarre aspect was a matter of conjecture. That they exceeded them in size is a matter of fact. The massive mandibles of Ischyodus Townshendi of the Portland age, or the enormous premaxillaries of Edaphodon gigas of the Chalk era, sufficiently testify that the possessors of such powerful dental machinery must have been of heroic