156 SUPPLEMENT TO THE 



44. Rhynchonella deflexa, Soio., sp. Dav., Sil. Mon., PI. XXII, figs. 24 — 27, and 



Sil. Sup., PL X, fig. 23. 



Since publishing ray description of Sowerby's Terehratnla deflexa, at p. 178 of my 

 ' Silurian Monograph,' the Rev. N. Glass has developed for me the interior of a typical 

 specimen which shows that it possessed the two short curved lamellae of the genus 

 Rlii/nchonella. 



45. Rhynchonella Wilsoni, Lav. Sil. Mon., PI. XXIII, figs. 1 — 9. 



This variable and important species has been fully described and illustrated at p. 

 1G7, and PI. XXIII of my 'Silurian Monograph.' Since then, at p. 193 of his "Die 

 Brachiopoden " ('Petrefactenkunde Deutschlands,' 1871), Professor Quenstedt proposed 

 to create a new genus, Wilsonia, for Bh. Wilsoni and similar species. Again, in the 

 magnificent volume of plates for the ' Explications de la carte geologique de France,' vol. 

 iv, Atlas, 1878, Professor Bayle gives the generic name Uncinulcs to RJi. Wilsoni, suh- 

 Wilsoni, (Ehlerii, imperator, &c., but does not describe or state on what characters he 

 founds his genus. At p. 690 of his ' Handbuch der Paliiontologie,' Professor Zittel refers 

 to Quenstedt's genus Wilsonia, adding Bayle's generic name as a synonym, but does not 

 admit either, and retains the old name RJiyncJi07iella. Mr. ffihlert informs me also that 

 Bayle has stated to him that the deep, excavated, muscular depressions in the ventral 

 valve was one of the principal characters that urged him and Quenstedt to propose a 

 distinct genus for the reception of Bh. Wilsoni and other similarly characterised species. 

 I am not, however, quite satisfied that the greater or lesser excavation of the muscular 

 area would be sufficient to warrant the creation of a new genus for such shells as Bh. 

 Wilsoni, Bh. siih-Wilsoni^ &c., nor have the proposers of the genera described its 

 characters. 



In the ' Annals and Magazine of Natural History ' for April, 1852, I referred to 

 the characters of the genus Bhpichonella, and gave complete figures of the interior of 

 both valves of Bh. Wilsoni, Bh. sub-Wilsoni,Bh. lacunosa, Bh. Boueti, and Bh. psittacea, 

 to show how variable is the depth or excavation of the muscular scars in the ventral 

 valves of those species, and how similar are the interior of the dorsal valves. 



