﻿1G8 



SUPPLEMENT TO THE CRAG MOLLUSCA. 



Terebratula granois, 1 Blumenbach. Supplement, Tab. XI, fig. 5 a — g, from the Cor. 



Crag ; Supplement, Tab. VIII, fig. 11 a — c, 

 from the Red Crag. 



Terebratula grandis, Davidson. Brit. Tert. Brach., p. 16, 1852. 

 Length, 5 inches ; breadth, 3$ inches ; depth, 2 inches. 



Localities. Cor. Crag, Ramsholt, Sutton, and near Orford. Red Crag, Walton 

 Naze, Sutton, and Waldringfield. 



Some years ago specimens of this species were procured by myself in great abundance 

 both at Sudbourn nnd Ramsholt, in the Coralline Crag, but recently they have become 

 somewhat scarce. This is the largest and most noble of the species that I am acquainted 

 with, and if I had to give it a name it should be called nobilissima, but unfortunately it 

 has too many synonyms. 



It is only within a few years that I have been able fully to display the internal 

 furniture of this species. A specimen in the British Museum presented by myself and 

 found at Ramsholt seemed to give fair promise of permitting the removal of the sand 

 from the interior, and I was enabled with care to exhibit in situ the short reflected loop of 

 which I have given a figure. All doubt is by this removed respecting its true generic 

 position, Prof. King having imagined that it was furnished with an internal apparatus 

 much prolonged, like that which he has taken for the type of his genus Waldheimia, 

 where the loop is extended to more than two thirds the length of the shell, whereas in 

 grandis it proves not to exceed one third. Mr. Davidson always imagined it to be a true 

 Terebratula, but he had not seen the perfection of the loop. I may further observe that 

 grandis possesses a very long spur or crura, and a very little more extension to this would 

 have united the two parts so as to form a ring like that which characterises the genus 

 Terebratulina. Whether this be so in the young state I have not been able to see. 



Specimens of grandis have come into my possession that measured nearly five inches 

 in length, and fragments have been found which indicate even larger dimensions. The 

 difference of size between the fry or infant state and the full-grown shell is so great as to 

 be not often observable in any animal. I have found what there is every reason to believe 

 is the young (and perfect) state of this species, with its longest diameter not more than the 

 twentieth part of an inch, which will give to the full-grown shell an increase of one 

 hundredfold at least in linear direction, and as in these large shells the young state of 

 the longest or perforated valve has entirely disappeared, probably to the extent of one 

 third of an inch, my estimate of these differences between the young and old is rather 



1 For generic and specific descriptions see Davidson, ' Monograph of the British Tertiary Brachiopoda,' 

 published by the Palseontographical Society. 



