GASTEROPODA. 53 



ford bed, and I have not met with it in the Lower Glacial Sands. It is an extremely 

 abundant shell in the Middle Glacial Sands, especially at Billockby, at which place I 

 have never met with the allied form terebra. The form in these sands is the var. triplicates, 

 fig. la, and 1c of Tab. IX of.' Crag Moll.' 



Turritella terebra, Linne. Crag Moll., vol. i, p. 74, Tab. IX, fig. 9. 



Localities. Fluvio-marine Crag, Bramerton. Chillesford Bed passim. Middle Glacial, 

 Clippesby, and Hopton. Upper Glacial, Bridlington. Post-glacial, March and Kelsey Hill, 

 Nar Brick-earth (Rose). 



This species is common in the Fluvio-marine Crag of Bramerton, but I have not met 

 with it in the Cor. Crag, nor with a clear example of it in the Red Crag. It occurs, but 

 is not very common, in the Chillesford bed at all its localities ; while at Clippesby (only a 

 mile from Billockby where we find the form incrassata alone), terebra exclusively occurs. 

 Compared with incrassata it is rare in the Middle Glacial, but specimens are not 

 unfrequent. I have not seen it from the Lower Glacial. It is common in the Post- 

 glacial gravel of March, and occurs at Kelsey Hill. Specimens of it sent to me by 

 Mr. Maw from the Severn Valley beds, as well as those from March, shew a tendency 

 in occasional individuals to approach the form incrassata, but there is no difficulty 

 in distinguishing a group of the one form from a group of the other. Mr. Rose 

 obtained it from the Nar Brick-earth, at West Bilney, and East Winch. 



Turritella erosa, Couthouy. Crag Moll., vol. \ } p. 76, Tab. IX, fig. 8. 



Turritella erosa, Couthouy. Boston Jour. Nat. Hist., 2, p. 103, Tab. Ill, fig. 1. 

 — clathratula, S. Wood. Crag Moll., vol. i, p. 76, Tab. IX, fig. 8. 



Locality. Upper Glacial, Bridlington. 



The shell, from Bridlington, was in the ' Crag Mollusca' assigned by me as a new 

 species {clathratula). I am now satisfied that it is identical with Couthouy's North 

 American shell erosa (polaris of Beck), which is given by Moller as a Greenland shell. 

 The statement at p. 83, of vol. iv, of ' Brit. Conch.,' that this shell has been found by me 

 in the Cor. Crag of Sutton is an error. I know it from no older East Anglian bed 

 that of Bridlington. 



- 



Turritella? penepolaris, S. Wood. Supplement, Tab. IV, fig. 20. 



Locality. Cor. Crag, near Orford and Sutton. 



A fragment of a shell from the Cor. Crag of Sutton, that I was unable to refer o 

 any existing species, has long been in my possession, but it was too imperfect 



