RHYNCHONELLA. 23 



seas, by dredging, in the Firth of Forth. Professor King showed me, likewise, some 

 years ago, a valve of this shell, brought up from the depth of thirty fathoms, at a distance 

 of twenty-five miles from the northern coast of Northumberland. It is therefore evident 

 that it occurs at a short distance from our coast in the recent state ; nor is there anything 

 extraordinary in this fact, as it is a well-known Boreal shell, found abundantly in the 

 northern seas near Greenland, Norway, Labrador, Melville Islands, &c. In the fossil 

 state, it unquestionably occurs in our newer Pliocene beds or Mammiferous Crag of 

 Bramerton, near Norwich, whence it has been collected by Sir C. Lyell, S. Wood, &c. ; and 

 several specimens may be seen in the collections of these gentlemen, as well as in those of 

 Mr. Fitch, 1 Professor Tennant, British Museum, &c. These last are from Postwick. It is 

 stated as occurring in similar beds in Ayrshire. 



Fig. 7, l ah , are recent specimens. 



Fig. 19, 19 ai , are the Crag specimens. 



1 Mr. Fitch informs me, that R. psittacea is found in a Crag containing a mixture of land, fresh water, 

 and marine shells; that Mr. Woodward called it " T. plicatilis, and rare," in his 'Geol. of Norfolk;' but 

 that he does not believe it rare, although he has only found two perfect specimens with both valves. Single 

 valves, in a very fragile, imperfect state are not uncommon : in one of Mr. Fitch's specimens, the deltidium 

 is distinctly seen. 



