BIVALVIA. 149 
Suttonensis was the antitype from which the recent pellucidus 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. 
Cunrenius cunrenuatus, 8. Wood. Crag Moll., vol. ii, p. 258, Tab. XXV, fig. 2 (as Gi 
tenuis, Phil.) 
CULTELLUS CULTELLATUS, S. Wood. Catalogue, Ann. & Mag. Nat. Hist., 1840, p. 240. 
Locality. Red Crag, Walton Naze. 
In the ‘Crag: Mollusca’ I referred some fragments of a cz/iellus from the Coralline 
Crag and some perfect valves from the Walton Red Crag to Philippi’s_ species ¢enais. 
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 cw/tel/atus, 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 czltellatus or Suttonensis were yvegarded as identical with pel/uccdus, then 
most assuredly the Hocene species, Grignonensis and afinis, would have to be treated as 
identical also, for the differences between Sudfonensis and Grignonensis, and between 
cultellus and afinis, are less than between the Crag shell and pellucidus. 
In « Brit. Conch.,’ vol. iii, p. 15, Soden pellucidus 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 pellucidus, while in the Red Crag list So/en pellucidus is given as a species from 
Aldeby. 
SoLEN SILIQUA, Tinn. Crag Moll., vol. 11, p. 255, MWA, ROX, WE Tc 
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. 
