496 



PLIOCENE MOLLITSCA. 



Buccinnnt cUidtuin. 



„ finiuarchianuni. 



„ fragile. 



„ ijroenlandicum. 

 Neptunea despecta} 



5, 5, var. carinata. 



„ „ var. decemcostata. 



„ ventricosa. 

 Troplion dafJiratus. 



var. attennata. 



Many northern species of Si-pho, includ- 

 ing the Icelandic S. Olavii ; some 

 northern Belas, but not 1>. tarriciiJa. 



Voln fopsis Larg illier ti. 

 „ norvegica. 



Natica affinU. 



TeUiiia {Macoma) ohliqua. 

 „ prsefciiids. 



Macfra elUptica, var. ohtruncata, and 

 others. 



I have obtained between ()00 and 700 species and well-marked varieties of 

 mollusca within an area of twenty yards square at this truly prolific spot. 



This zone is specially characterised by the first appearance in the Crag basin 

 of dextral Neptnncas of a distinctly arctic and carinated type, though the sinistral 

 Waltonian species, N. contraria, is still the more abundant.^ 



In the group of Red Crag deposits, for which I have adopted the name 

 " Newbournian," the southern element is not so preponderant as it is in the 

 Waltonian, and it contains a larger percentage of northern and recent species. 

 The localities, the fauna of which I refer to this division, occur in an area to the 

 north and north-east of those last described at Foxhall, Waldringfield, Newbourn 

 and elsewhere as shown on the map. Fig. 4, 



Tlie latest or Butleyan division of the Red Crag may be studied at Bawdsey, 

 Alderton, Hollesley, Sudbourn, Butley, and in the stack-yard just below Chillesford 

 Church, a district lying to the north-east of the Newbournian area (see map. 

 Fig. 4). This group of deposits has been long known to contain a molluscan fauna 

 of a decidedly northern as well as of a more recent type. Including, in addition 

 to some of the shells given above as characteristic of the earlier part of the 

 Red Crag, the following species may be specially mentioned : 



JSassa iucrassata, var. /3. 

 Bucciniim, tmdatum, var. cwrulea. 

 Purpura laplllus, recent vars. 

 Ne'ptunea antiqua, recent British form. 

 AnomalosipJiO alius. 

 Natica catena. 

 Trochus tumidus. 



Nucida GobboJdige. 

 Loripes divaricates. 

 Cardium angustatum. 



,, (Serripes) gro'iilaiidictnn. 



Astarte compressa. 

 Tellina praitcnuis. 

 Mactra constricta. 



' In my paper on the Crag of Essex (Waltonian), Quart. Journ. Geol. Soc, vol. Ivi, p. 718, 1900, 

 tliis shell was regarded as equivalent to the recent British form JV. antiqua. In the present work 

 I consider it to be a different and northern species, N. despeda (see Vol. I, pp. 160 et seq.). 



- A photograph o4: the Oakley section appeared on p. 483 of the first volume of this work. 



