RHYNCHONELLIDtE. 



163 



Castle ; Brorasgrove, Lickey ; Worcester Beacon, Malvern ; May Hill ; Huntley Hill ; 

 Chirbury ; Gunwick Mill, Gullet Wood, Howler's Heath, &c., west of the Malverns ; 

 Avery Green, and Woodford Green, near Tortworth ; at Mandinam, Pen-Ian, and Castel- 

 craig-gwyddon, Llandovery ; Trecoed, Builth, &c. 



Mr. Salter mentions that at May Hill and in the Malverns St. lens is more abundant 

 than Pent, ohlongus ; St. lirata being found also in the same beds. In the Shropshire 

 and western districts it is less so. 



In the Geological Survey Beports of Canada Mr. Billings quotes St. lens from South- 

 west Point, and the Jumpers, both in the Island of Anticosti. 



Genus — Rhtnchonella, Fischer, 1809. 

 Be/.—" Introduction," p. 93. 



This excellent genus has been so often described in the present work, that it will not 

 be necessary to again refer to the subject, further than to mention that since the pub- 

 lication of my " General Introduction " the anatomy of one of its most characteristic 

 living types has been admirably described and illustrated by Mr. Albany Hancock, — in 

 the ' Philosophical Transactions ' for the year 1858. 



Much still remains to be done before the multitude of species at present referred to 

 the genus by different authors can be properly Aveeded, and classed according to the 

 modifications presented by their interiors. Indeed, Prof. Hall has already detached 

 from it certain forms upon which his genus Eatonia is founded ; and it is very 

 probable that, when the interiors of more of the species shall have been discovered 

 and properly studied, it may be necessary to divide the numerous species into several 

 minor sections, or even genera. In all the published lists of Silurian Bhynclionelloe a 

 number of species which do not belong to the genus have been provisionally admitted by 

 several palaeontologists, and necessarily so until the interiors are known ; and although 

 I believe I have successfully detached some of these species, and placed them in their 

 proper genera, there still remain a few of whose correct position I feel very uncertain, 

 and they must, I suppose, be temporarily allowed to encumber the genus.^ In the 

 second volume of the ' Memoirs of the Geological Survey ' Prof. Phillips proposed the 

 generic designation of Hypothjris for the plaited Terebratulse ; and in his ' British 

 Palaeozoic Possils' Prof. M'Coy adopts that of Hemithyris for our British Silurian 

 oi BhyncJionella ; these designations, however, have been found to be synonyms 

 of the genus distinguished by Pischer de Waldheim in 1809. 



* It is a useful canon in palaeontology, that when, from imperfect materials, the exact genus of a new 

 form cannot be ascertained, the describer shall place it in some leading and well-known group, such 

 as Rhynchonella, Spirifera, Terebratula, &c., instead of under a new but doubtful name. By this rule 

 frequent changes are avoided, the leading genus being understood to be a temporary storehouse for 

 indistinct but allied forms. — J. W. S. 



