1871.] EGERTON LIASSIC CHIM^KOID PISH. 275' 



Fig. 5. Protopteris peregrina, Newberry, impression of stem, oue-foiirfch the 

 natural size : xx, remains of petioles. 5 a, scar, natural size, show- 

 ing bundles of vessels at base ; 5 b, portion of a vascular bundle, mag- 

 nified, showing scalariform vessels and cellular tissue; be, scalari- 

 form vessel, highly magnified. 



Fig: 6. Lower part of stem of the same, with aerial roots, one fourth the na- 

 tural size. 6 a, one of the roots, natural size. 



Fig. 7. Vascular bundle of Bachiopteris, natural size ; 7 «, 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. Nceggerathia 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 Chaiiiman (Prof. Morris) remarked on the four different con- \ 

 ditions exhibited by existing tree ferns : — first, with roots running \ 



down the stem ; secondly, the lower portion with oval scars ; these j 



are, thirdly, further up the stem, rhomboidal vertically ; and, fourthly, j 



higher up still, rhomboidal horizontally ; so that were the plant fossil, •^ 



distinct genera and species might be founded upon the different parts. 



Apeil 5, 1871. 

 The following communications were read :-— 



1. On a new Chim^eoid Fish from the Lias o/Ltme Regis (Ischy- 

 odus orthorhinus, c? )• By Sir Philip Geey Egeeton, 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 re- 

 sembled 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 posr 

 sessors of such powerful dental m«,chinery must have been of heroic 



