Geological Society. 467 



^ ( Frustules with a terminal crest minutum. 



~ ' \ Frustules not crested 3 



r Forms large masses ; frustules large without terminal 



I puncta geminatum. 



I Very minute; frustules minute with two conspicuous 



L teVminal puncta pohlicpforme. 



f Frustules with a terminal crest cristatum. 



■ \ Frustules not crested 5 



. J Frustules curved minutiss'mium. 



"'■ \ Frustules not curved 6 



(Marine ; lateral surfaces not striated, front with striae 



extending from the terminal puncta paradoxum. 

 Fresh water; lateral surfaces striated, front surfaces 



without longitudinal striae 7 



{Front view nearly linear; lateral surfaces lanceolate ... dichotomum. 

 Front view broadly cuneate ; lateral surfaces obovate or 



clavate Berkeleil. 



PROCEEDINGS OF LEARNED SOCIETIES. 



GEOLOGICAL SOCIETY. 



Feb. 22, 1843. — A paper was read " On some new species of Fossil 

 Chimseroid Fishes, with remarks on their general affinities," by Sir 

 Philip Grey Egerton, M.P., F.G.S. 



The number of described species of Chimaera— soft-boned fishes 

 of singular forms — is very small, whether existing or extinct. They 

 were tirst recognised in a fossil state by Dr. Buckland in 1835. 

 The original memoir comprised descriptions of four species ; two 

 others were added by Professor Agassiz. The list was soon after- 

 wards augmented by two species from the Stonesfield slate, con- 

 structed by Dr. Buckland from some enigmatical specimens forwarded 

 by the author under the impression that they had some resemblance 

 to the subjects he was engaged upon. A ninth species came from 

 the Caen oolite. A tenth has been described by Professor Owen in 

 his ' Odontography' from specimens in the Hunterian collection, and 

 Professor Agassiz has named an eleventh in the museum of Lord 

 Enniskillen, from the gault. Sir P. Egerton, in the present memoir, 

 doubles the number. With one exception he founds his characters 

 on the lower jaws of the animals, avoiding the risk of ascribing spe- 

 cific differences to teeth derived from one and the same species, 

 varying in form according to their position in the mouth. 



The characters of the new species are as follows :^ 

 1. C neglecta. — Maxillary plate, left lower jaw : length 6 lines ; 

 depth at the symphysis 2 lines ; ditto at the medial angle of the 

 dental edge 3 lines ; length of the dental edge 3^: lines ; anterior 

 division of ditto 1| line ; posterior ditto ditto 1| line ; length of the 

 heel 2| lines ; exterior convex ; exposed surface slightly furrowed ; 

 base expanded and vertically striated ; two depressions, the anterior 

 one broad, the posterior narrow and deep. Stratum, great oolite : 

 locality, Stonesfield. 



