Vol. 52.] PLIOCENE DEPOSITS OF HOLLAND. 755 



that no beds equivalent to its upper horizons were known either in 

 Belgium or Holland. 1 A careful analysis of the different faunas 

 induces me to agree with him as to the two first propositions, but 

 not as to the third. It seems to me that the upper and by far the 

 larger of the Dutch beds regarded by Dr. Lorie as Scaldisien are 

 considerably more recent than that formation.' 



The resemblance between the "Walton Crag and the Scaldisien 

 (including the Poederlien) of Belgium is very close. Among the 

 mollusca found at Walton there are 120 which occur abundantly, 

 and which may be taken as representative species, 2 and of these 91 

 are found in the latter deposits. Both are characterized by the 

 first appearance and the great abundance of the sinistral form of 

 Trophon (Chrysodomus) antiquus* The dextral variety has not been 

 met with in the Scaldisien, and a single specimen of it only in 

 an upper bed at Walton, but it appears in increasing abundance in 

 the later beds of the Crag, where the left-handed form becomes 

 correspondingly scarce. 



Among the rarer mollusca of these deposits there are a number of 

 extinct and southern species, 4 which were apparently dying out at 

 that period, as many of them are abundant in the Coralline, but 

 are not found in the upper beds of the Red Crag. The latter 

 moreover contain northern shells, including the Arctic forms 

 Buccinum grosnlandicum, Scalaria groenlandica, Amaura Candida, 

 Natica groenlandica, N. helicoides, Leda lanceolata, L. minuta, 

 and Cardium grcenlandicum, which are not known either in the 

 Scaldisien or from Walton or any older horizon. 



In the Poederlien, a slightly newer zone, which has recently been 

 separated from the Scaldisien by M. Vincent, the dextral form of 

 Trophon occurs, though not abundantly, associated with a few 

 specimens of the northern but not exclusively Arctic shell 

 Chrysodomus despecta, but these are not characteristic of the fauna, 

 the general facies of which is southern rather than northern. 

 There is very little difference between the Scaldisien and the 

 Poederlien. With few exceptions, the species of mollusca found in 

 them are common to both, and they are not more unlike than the 

 lower is to the upper bed at Walton. From the latter, as from the 

 Poederlien, a fauna slightly more boreal than that of the bed under- 

 lying it has been obtained. 5 



The following lists show — A, the species abundant at Walton which 

 are found also in the Scaldisien and Poederlien ; B, the extinct and 

 southern forms occurring in them, but not in the upper Red Crag ; 

 and C, the northern and recent shells characteristic of the latter, 

 which are not present in the older beds. 



1 'Pliocene Deposits,' etc. p. 211. 



2 I am indebted for this information to Mr. P. F. Kendall, F.G.S. 



3 The Scaldisien was originally called the ' Zone a Trophon antiquum'. 



1 44 extinct and 17 southern in the Scaldisien (including the Poederlien \ 

 and 40 extinct and 11 southern at Walton. 



5 The distinction between the upper and lower beds at Walton was first 

 pointed out by Mr. Kendall. 



