THE BRACillOPODA. 13 



5. — Teuebratula Buckmani, Davidson. 



1851. Terebkatula Buckmaxi, Davidson. British Brack. 

 Paleoont. Soc, plato vii., figures 15-lG. 



The specimens from this distiict are generally a very slight 

 variation of the Cotteswold forms, that is, they are thinner and 

 have a rather flattish dorsal valve. Tereh. Bachnani, however, is 

 rather variable, and gradually passes into those varieties which 

 have been sej)arated by Mr. Walker under the name of variety 

 T. Bachmanhna. All these occur together in a peculiarly irony 

 stone (zone of Stophan. Humphriesianum) near Half-way House, 

 Oompton. The forms which agree witii the true Tereh. Bachmani 

 are rather rare, but the variety Ter. Bmhnaniana is much 

 commoner. 



Localities. — Near Half-way House and at Oborno (Dorset), 

 also near Cheltenham (Grloucestershire). 



Ohs. — Some authors have placed Tereh. Biccloiiaiiisisa, synonym 

 of Tereh. ventricosa Hartmann, but Mr. Davidson observes 

 " Mr. Deslongschamps adds to his description of this species fT. 

 ventricosa) a long synonomy, among which he places the shell to 

 which I gave the name of Tereh. Bachinani, but I cannot admit 

 this identification when I compare it with Grerman and French 

 examples and figures of Hartmann's or Zicten's shell. ^' 



5a. — Terebkatula Buckmani, varietjj Buckmaniana, 



Walker. 



1878. Tereb. Buckhani, var. Buckmaniana, Davidson, British 

 Brachiopoda Pala)ont. Soc, plate xix., 

 figures, 14-17. 



Along with Tereh. Buclcmani occur numerous varieties, such as 



are well represented by Mr. Davidson in the above reference. 



Those forms differ chiefly from T. BucJcinani in being more or 



less distinctly biplicated and much thicker, or else broader and 



* Davidson, British Fossil Biacliiopoda, PaLeont. Soc. 1876, page 127, 



vol. XXX. 



