THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE III. VOL. IX. 



No. VII.— AUGUST, 1892. 



OI^ 1(3-1 nsrjLiL ^^I^TIG^LES. 



I. — On the Abierioatst Paleozoic Gasteropod, Trematonotus 

 (Hall emend. P. Fischer), and its Identification in Britain; 

 WITH Description of a New Species. 



By R. BuLLEN Newton, F.G.S. ; 



of the British Museum (Natural History). 



(PLATE IX.) 



PROFESSOR JAMES HALL'S ^ discovery, in 18fi4, of liis 

 remarkable genus Trematonotus, in the Niagara rocks of North 

 America, formed an interesting and valuable addition to his re- 

 searches in concliological science. 



The special features of this shell consist in its Bellerophontoid 

 appearance, coupled with the presence of a single row of isolated 

 perforations on the central part of the dorsal surface. It was some- 

 what erroneously regarded by its author as a sub-genus of Leveillia^ 

 [Porcellia),^ though its unique characters would mark it as a distinct 

 form, and probably more intimately related to the well-known 

 Haliotis of our modern seas than to any other known shell. 



Mr. F. B. Meek,* in 1866, considered the characters of Hall's 

 genus as affording the evidence required to finally prove the Proso- 

 branchiate affinities of the Bellerophontidge, an opinion which the 

 late Professor de Koninck ^ advanced as long ago as 1844: after 

 a careful comparison of the genus Emarginida with the extinct 

 Bellerophon. Tlie views of the Belgian palfeontologist on this point 

 were very partially recognized, and only received adoption from 

 Alcide d'Orbigny '^ in 1852, and Pictet' in 1855, since which dates 

 they were classed with the, Heteropods, until Meek's observations 

 led to a reconsideration of the subject, and a general acknowledge- 

 ment that the banded shells of the Prosob ranch iate MoUusca must 

 henceforth include the family of the Bellerophontid^. 



The type species of Trematonotus, and the only one then described, 

 was T. alpheus, a name since ignored in favour of McChesney's 



1 Eighteenth Eeport Regents University, New York, 1864, p. 347," Twentieth 

 ditto, 1867, pi. XV. figs. 23, 24. 



2 R. B. Newton, Geol. Mag. 1891, PI. VI. p. 202. 



2 C. Leveille, Mem. Soc. Geol. France, 1835, vol. 2, part 1, p. 39. 



* Proc. Chicago Ac. Sci. 1866, vol. 1, p. 9. 



5 Desc. Animaux Foss. Carb. Belgique, 1844, pp. 334-338. 



^ Cours elem. Paleontologie Geologie, 1852, vol. 2, p. 33. 



' Traite Paleontologie, 1855, ed. 2, vol. 3, p. 287. 



DECADE III. — VOL. IX. NO. YIII. 22 



