﻿BIVALVIA. 



149 



Suttonensis was the antitype from which the recent pettucidus has descended through such 

 modifications as are exhibited in the Aldeby specimen. I have had the recent shell 

 figured beneath these two (Tab. X, fig. 16) for comparison with them. 



Cultellus cultellatus, S. Wood. Crag Moll., vol. ii, p. 258, Tab. XXV, fig. 2 (as C. 



tenuis, Phil.) 



Cultellus cultellatus, 5. Wood. Catalogue, Ann. & Mag. Nat. Hist., 1840, p. 245. 

 Locality. Red Crag, Walton Naze. 



In the ' Crag Mollusca ' I referred some fragments of a cultellus from the Coralline 

 Crag and some perfect valves from the Walton Red Crag to Philippi's species tenuis. 

 This I now believe to have been an error. The Red Crag specimens, which are perfect, 

 enable me to refer them to a new species under the name cultellatus, which is the name 

 I proposed for both the Coralline and Red Crag forms in my catalogue of 1840. 



With respect to the fragments from the Coralline Crag, however, they are insufficient 

 for any satisfactory determination, and may probably be fragments of the before- described 

 Suttonensis. 



If either cultellatus or Suttonensis were regarded as identical with pettucidus, then 

 most assuredly the Eocene species, Griynonensis and affinis, would have to be treated as 

 identical also, for the differences between Suttonensis and Griynonensis, and between 

 cultellus and affinis, are less than between the Crag shell and pettucidus. 



In ' Brit. Conch.,' vol. iii, p. 15, Solen pettucidus is said to be a Coralline Crag species, 

 but in the list to Mr. Prestwich's Cor. Crag paper Cultellus tenuis is mentioned, 

 and not pettucidus, while in the Red Crag list Solen pettucidus is given as a species from 

 Aldeby. 



Solen siliqua, Linn. Crag Moll., vol. ii, p. 255, Tab. XXV, fig. 7. 



Localities. Red Crag, Sutton. Fluvio-marine Crag, Bramerton. Chillesford bed, 

 Aldeby ? Middle Glacial, Hopton ? 



This is the only species yet known from the Fluvio-marine Crag in which it is rare. 

 Fragments of a Solen have occurred at Aldeby and at Hopton, but neither of them suffi- 

 ciently characteristic to permit a certain reference to this species. I have therefore given 

 it from the Chillesford Bed and from the Middle Glacial sand with doubt. The species 

 is still unknown to me from the Coralline Crag. 



