﻿BIVALVIA. 



125 



Charlesworth has shown me a specimen of suborbicidaris from the Red Crag in a crypt 

 with a P kolas. 



The new species of Kellia described by Forbes in his 'iEgean Report/ 1843, 

 cannot now be found, and his short descriptions, unaccompanied by figures, are insufficient 

 for specific determination. Perhaps his Kellia transversa may be the same as my 

 Scacchia cycladia, but I cannot alter the name of my shell upon such uncertainty. 



Scintilla ambigua, Nyst. Crag Moll., vol. ii, p. 120, Tab. XII, fig. 11 (as Kellia 



ambigud) . 



Scintilla ambigua? Desk. An. sans. Vert., t. i, p. 700, pi. xlix, figs. 13 — 15. 



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

 Chillesford Bed, Chillesford and Alcleby. 



In Mr. Jeffreys' list of Cor. Crag shells ('Quart. Journ. Geo. Soc.,'vol. xxvii, p. 139) 

 this species is referred to Erycina pusilla, Phil., but in the same Journal subsequently, at 

 p. 493, Mr. Jeffreys says that "Kellia ambigua is not Erycina pusilla, Phil., but Scintilla 

 Parisiensis of Conti." He has since written to me that he now refers it to Kellia 

 Geoffroyi, Payr, of which he sent me a specimen for comparison. I find that shell, 

 however, to be covered with fine radiating lines, of which I can detect no trace in the 

 numerous specimens of ambigua in good preservation which I have examined. I have 

 therefore retained the name ambigua, Nyst, under which I originally described this shell, 

 merely changing the generic appellation. 



The name of Scacchia elliptica is given in the same list by Mr. Jeffreys, at p. 485, as 

 a species new to the Red Crag. On application to Dr. Reed, of York, in whose cabinet 

 is the specimen on which this introduction of the species as a Red Crag shell is founded, 

 he obligingly sent it to me for examination, and I find it to belong to Scintilla ambigua, 

 which I had given as a Red Crag species in 'Crag Moll.,' vol. ii, p. 121. Scacchia 

 elliptica is abundant in the Cor. Crag at Sutton, as is also Scintilla ambigua, but the latter 

 becomes very rare in the newer Formations (where it appears to have died out), and is, 

 moreover, exceedingly variable in its outline as well as in the degree of its tumidity. 



Montactjta bidentata, Mont. Crag Moll., vol. ii, p. 126, Tab. XII, fig. 17. 



Localities. Cor. Crag, Sutton, and near Orford. Red Crag, Walton Naze. Chilles- 

 ford Bed, Aldeby. Middle Glacial, Hopton. Post Glacial, Nar Brickearth, at Pentney. 



This species has been obtained by Messrs. Crowfoot and Dowson from Aldeby, by 

 my son (a single valve) from Hopton, and by Mr. Rose from Pentney. The specimen 

 upon which the species was given as from Bridlington in 'Mem. Geol. Survey,' vol. i, p. 

 409, 1846, was in the Bowerbank collection now in the British Museum, and had, 



