PLATE II. 



(Carbon iferotjs Species.) 



Fig. 



1__8. Terebratula vesicularis, Be Koninck. Different varieties of shape. Figs. 1, 2, 



3, 4, 6 from the Yoredale Rocks, Wensleydale, 

 Yorkshire, and collection of Mr. E. Wood. Figs. 

 5, 8 from Pilsbury Castle, Longnor, Derbyshire. 

 Museum of the Geological Survey. Fig. 7 enlarged 

 from a specimen in the Cambridge Museum, 

 erroneously identified with Ter. seminula of 

 Phillips by Professor M'Coy. 



9,10,11. Spirifera duplicicosta, Phillips. Young individuals ? according to Professor 



Phillips and De Koninck, from Thorpe, Cloud Hill, 

 Dovedale, and Park Hill, Longnor ; but these very 

 transverse specimens lead me to doubt the identi- 

 fication, and perhaps they should be considered 

 the young of Sp. striata. 



12,13. — striata, Martin, var. attenuata, SoAverby. These two examples are 



drawn from the original specimens figured in the 

 'Mineral Conchology' as Sp. attenuata. Kildare, 

 Ireland. 



14. — — Millecent. Collection of the late Mr. Daniel Sharpe. 



15, 16. — — Var. with very small ribs. From Dovedale, Derby- 



shire. Museum of Practical Geology. 



17. — — From the Craven district, Yorkshire, and collection 



of Mr. E. Wood. 



18. — — A remarkable variety, with very deep sinus, and 



produced mesial fold. Bolland, in the collection of 

 Mr. J. de C. Sowerby. Another similar example 

 may be seen in the British Museum. 



19. — — Interior of the dorsal valve, with perfect spiral 



appendages. 



20. — — This illustration is taken from a beautifully perfect 



specimen in the Cambridge Museum, in which 

 the matrix enveloping the spirals had been care- 

 fully removed by the means of acid; the shell 

 and its spiral lamellae being silicified. The spirals 

 are here represented, as seen by removing a portion 

 of the dorsal valve ; so that the back and front 

 view of these appendages are completely illustrated 

 in figs. 19 and 20. 

 21- — — Interior of the ventral valve, to show the muscular 



impressions, &c. From a specimen in the British 

 Museum. 



