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SUPPLEMENT TO THE CRAG MOLLUSCA. 



the ' Crag Mollusca,' remains of colour in the Crag specimens (which are fragmentary) 

 induced me to refer them to the Mediterranean form. I was misled by Herrmannsen 

 (who gave the date of the name Macha as of 1815 instead of 1835) in using that generic 

 name for this shell. Solecurtus antiquatus is mentioned in ' Brit. Conch.,' vol. hi, p. 7, 

 and by the author of that work in his list to Mr. Prestwich's Cor. Crag paper, as a 

 Coralline Crag shell ; while Mr. Bell, in his paper on the " English Crags " (' Proc. Geol. 

 Association/ 1872) inserts it as a Red Crag species. The only specimens, however (which 

 are all fragmentary), that I have seen from any part of the English Crag belong either to 

 strigillatus or Candidas. 



Much difficulty seems still to exist respecting the siphonal side of shells of this family. 

 In 'Brit. Moll.,' vol. i, PL I, as I before pointed out ('Crag Moll.,' vol. ii, p. 254), the 

 illustrations for this genus, as well as for other genera in the same plate, show the foot 

 protruded on the siphonal or ligamental side of the shell, and the same misrepresentation 

 is repeated in the generic illustrations in PI. I, vol. hi, of ' Brit. Conch.' The sinuated 

 mark in the interior of a bivalve, when it exists (as left by the impression of the 

 retractor muscles), is on the side which bears the ligament, and the siphons are protruded 

 in that direction, the foot going in the opposite. 



Cultellus Suttonensis, S. Wood. Supplement, Tab. X, fig. 15. 



Spec. char. C. Testa transversa, oblongo-lineari,rectiuscula, laevigata, tenuis, fragilis, 

 antice breviore, rotundato-truncata, postice longiore et latiore valde i nee qui -lateralis, in 

 valvula dextra bidentatis, in valvula sinistra tridentatis. 



Length f of an inch. 



Locality. Cor. Crag, Sutton. 



Some fragments of this shell have been long in my cabinet, and I had imagined them 

 to belong to the same species as that from the Red Crag of Walton, which T had in the 

 ' Crag Mollusca ' figured under the name of tenuis, Phil. I now believe these to be 

 specifically different, and a perfect specimen having been obtained by Mr. Robert Bell, I 

 have figured it as above. The shell differs from pellucida in the absence of curvature 

 and the broadness of the posterior extremity ; it differs also from the Upper Eocene 

 species, C. Grignonensis, Desh. ('An. sans. vert, du Bas. de Par.,' Tom. l, p. 157, PI. VII, 

 figs. 13—15) in its outline, that shell approaching nearer to pellucidus than does our own 

 shell. A fragment in my possession indicates a length of more than three fourths of an 

 inch. 



A specimen of Cultellus from the Aldeby bed sent me by Messrs. Crowfoot and 

 Dowson is represented in Tab. X, fig. 14. This seems to be intermediate between the 

 Cor. Crag form Suttonensis and the recent form pellucidus, as the formation from which 

 it conies is correspondently intermediate in time. It is therefore not unlikely that 



