TEREBRATULA. 71 



of the longitudinal depression or Implication so strongly marked in adult examples of the 

 Swedish type. 



In Belgium, T. depressa is perfectly characterised, and abounds in the Tourtia of 

 Tournay, Montignies-snr-Roc, and Gussignies, whence Lamarck obtained his speci- 

 mens ■} but in England, we are at present only acquainted with the single locality of 

 Farringdon, where the race does not seem to have attained the large dimensions of the 

 Belgian type. Our British examples are commonly shorter, and more stinted in their 

 growth, and the mesial fold is at times more produced than in the generality of Belgian 

 individuals. 



T. depressa does not seem to have been yet discovered in France, no mention of it 

 being made in the ' Palgeontologie Francaise.' 



In 1847, Viscount d'Archiac believed the species new, and named it Terebratula 

 nerviensis." In 1846, the same shell was mistaken by Mr. Morris, for T. ovalis 

 (Lamarck), which last belongs to the Jurassic epoch, and is specifically distinct. 3 And 

 in 1848 Professor Bronn considered T. longirostris to be a synonym of the Lamarckian 

 T depressa ; an opinion in which I am unable to concur. 



Many varieties might be noticed, but from these passing one into the other they do 

 not in my opinion require distinguishing denominations. Ter. Viquesneli, D'Archiac, is 

 one of them, it is found likewise at Farringdon, but appears to be simply a young state 

 of the Lamarckian species. 



Plate IX, fig. 9. One of the largest examples hitherto discovered in the Upper 

 Green Sand of Farringdon. The valves are commonly found 

 detached. 

 ,, fig. 10. A ventral valve, from the collection of Mr. Sharpe. 



„ fig. 11. A specimen drawn from two separate valves, in the collection of 



Mr. Sharpe. 

 ,, figs. 12 — 21. Different examples, ages, and varieties, of T depressa ; figs. 



14 and 17 from the collection of Mr. Lowe; figs. 18 

 to 21, from that of Mr. Sharpe. 

 ,, figs. 22 — 23. A young specimen of T. Viquesneli, D'Archiac, from Farring- 

 don, in the collection of Mr. Sharpe. 

 ,, fig. 24. A copy of the Belgian figure of T Viquesneli, published by Viscount 

 d'Archiac, for the sake of comparison. 



1 The original specimens are now in Baron Delessert's collection, and were figured by myself in the 

 •Annals' for 1850. 



2 This species was admirably described and figured by the distinguished French author in his "Rapport 

 sur les Fossiles du Tourtia," ' Geol. Trans. France,' 1847. 



3 Ter. Repeliniana, D'Orb. (' Prodrome,' vol. ii, p. 25, 1850), from the White Coral Rag, near Vurey 

 (Isere), &c, bears more resemblance to Ter. depressa (Lamarck), than any other Terebratula with which I 

 am acquainted. 



10 



