18 BRITISH TERTIARY BRACHIOPODA. 



stages of growth, the edges of the valves do not encroach upon one another, there being 

 simple adaptation of the margins in an even line from the excessive thinness of the shell 

 at the line of junction ; when, however, the shell has attained the length of three inches, 

 the front edge is rather suddenly produced with an abrupt termination, which is received 

 in a notch in the opposite valve." 1 The foramen is also variable in dimensions, sometimes 

 so large as almost to admit the tip of the small finger, being doubtless the largest 

 Terebratula as yet come under our notice. The internal apophysary skeleton is short, 2 

 never exceeding a third of the length of the valve ; we therefore are at a loss to make out 

 why this shell is announced by Professor King 3 as an illustration of his genus Waldhemia, 

 where, according to that author, the process extends to near the frontal margin. 



In England this species is common to both the red and coralline crags, but larger and 

 more abundant in the last, where it is found in great numbers at Sudbourn, near Orford, 

 on the estate of the Marquis of Hertford, and of the road leading from Aldborough to 

 Leiston. In the red crag the specimens rarely have the two valves united, and are in 

 general much water-worn, the best localities being Sutton, Walton on the Naze, Ramsholt, 

 Felixtow, &c. On the continent it has been met with in several localities by Mr. Nyst, 

 at Pellenberg near Louvain, and in the Crag of Antwerp in Belgium. In France it is 

 stated to have been found a la Gresille near Doue ; and during a late journey to Valogne, 

 M. de Gerville showed me a basketful he had obtained from Bohon in the Dep. de la 

 Manche. Blumenbach's types were obtained from Osnabruck. 4 



Plate I, fig. 18. A specimen from the Red Crag, in the collection of Mr. S. Wood. 



„ II, fig. 1. Illustrates a remarkably fine specimen in the Museum of Mr. Bowerbank. 



„ fig. 2. Interior of the large valve. 



,, fig. 3. Interior of smaller valve, showing the loop, which, though incomplete, 

 did not extend to a greater length, from a specimen in the collection 

 of M. Bouchard. 



„ figs. 4, 5, 6, 7. Different ages. 



,, fig. 8. Enlarged portion of the beak from a young shell, showing that at a 

 certain age the deltideum was only lateral. 



1 'Mag. of Nat. Hist.,' vol. i, 1837. 



2 From the coarseness of the sand which fills the interior, it has been as yet impossible to clear the 

 apophysis completely ; but, from a specimen in M. Bouchard's collection, it evidently does not exceed the 

 dimensions stated. 



3 ' A Monograph of Permian Fossils,' Pal. Soc, p. 69. 



4 There appears to be a difference of opinion as to the age of this deposit ; De Miinster places it in 

 the older Pliocene, while Goldfuss considers them Miocene, or middle Tertiary. See M. le Viscomte 

 D'Archiac's valuable notes on this subject, ' Hixtoire des Progres de la Geologie,' vol. ii, 2d part, 

 p. 849, 1849. 



