PROCEEDINGS 



THE GEOLOGICAL SOCIETY OF LONDON, 



Vol. IV. Part I. 1843. No. 96. 



June 21. — The following papers were read : — 



1. " Supplement to a Memoir on the Fossil species of Chimara.'^ 

 By Sir P. Grey Egerton, M.P., F.G.S. 



Since the author's former memoir was communicated to the So- 

 ciety, he has seen in the coll. ction of Mr. Dixon a new and striking 

 addition to the genus Ischyodus. The specimen is from the chalk 

 of Southeram, and presents two dental plates only slightly dislocated 

 from their natural juxtaposition. At first sight these would appear 

 to be the dental armature of the lower jaw, corresponding nearly in 

 size to the lower mandibles of Ischyodus mantelli. A closer exami- 

 nation has satisfied Sir Philip Egerton that they are in reality the 

 intermaxillary plates of the upper jaw of a most gigantic chimeeroid. 

 They exceed in size the corresponding teeth of Ischyodus townshendi, 

 the largest species hitherto found by one third. As compared with 

 the intermaxillaries of that species they are broader, more compressed 

 and less robust in antero-posterior diameter, and less hooked at the 

 extremity. The form of the cutting edge is not truncate, as in the 

 recent Chimara, but prolonged to an acute angle, and bent down- 

 wards like the upper mandible of a bird of prey. The symphysis is 

 smooth and slightly hollowed. The thin polished investing laminae 

 of compact dentine is seen adhering to the surface of the tooth. On 

 the interior surface this is marked with broad transverse irregulari- 

 ties similar to, although less distinct than, those seen in the recent 

 Chimcera. A fragment in Mr. Dixon's collection gives evidence of 

 having belonged to an individual of much larger size than that which 

 furnished the specimens here described. Sir Philip Egerton proposes 

 to name this species Ischyodus gigas. 



2. " On the occurrence of the remains of Insects in the Upper Lia.s 

 of the county of Gloucester." By .James Buckman, F.G.S. 



The remains described in this paper were discovered by Mr. Buck - 

 man in a thin seam of argillaceous limestone in the upper lias beds 

 at Dumbleton, a village twelve miles from Cheltenham, to which his 

 attention had been directed by Mr. Brodie, who had suspected the 

 existence of insect remains in the stratum. The section of Dum- 

 bleton Hill, which is a liassic outlier, presents the following beds. 



VOL. IV. PART I. R 



