202 MB. G. W. LAMPLTTGH ON THE SPEETON SEEIES [May 1 896, 



quadratus, Roem.). But from the spoil-heaps of the abandoned 

 mines near Acre House I have also obtained a few fragments of 

 B. jaculum, along with two pieces of Ammonites (Hoplites) cf. regalis 

 (noricus of Judd) and a fragment of Olcostephanus, near Astier- 

 ianus, d'Orb., which appear to have been embedded in a matrix of 

 clay with ironstone- grains. 



The ammonites collected, with the above exception, are all deep- 

 whorled Olcostephani (subgenus Polyptychites of Pavlow), including 

 Olcostephanus {Polyptychites) BlaJci, Pavl. ; 0. (P.) Beani, Pavl. ; 

 and 0. (P.) cf. ramulicosta, Pavl. ; which are all species charac- 

 terizing the upper part of the 'Zone of Belemnites lateralis' at 

 Speeton. 



These cephalopoda alone are sufficient to fix the correlation with 

 the Speeton section, and their evidence is confirmed by several other 

 fossils common to the two areas ; among others being Exogyra 

 sinuata, var. (a well-marked form which I think should rank as a 

 separate species), Astarte senecta, Bean MS., Pholadomya, sp., Area, 

 sp., etc. Many of the lamellibranchs, however, such as the Trigonice, 

 Cucullcpaz, etc., and some of the brachiopods, which abound in the 

 Claxby Ironstone and the Spilsby Sandstone, have not been found 

 in the Speeton Clay, while other fossils, like certain species of 

 Lingv.la, Nucula, etc. which are plentiful at Speeton do not occur 

 in Lincolnshire. This differentiation of the contemporary faunas is 

 evidently the outcome of the different conditions of depth, nature of 

 sea-bottom, etc., prevalent in the two areas ; and their mutually 

 complementary character at these and other horizons will prove of 

 the greatest value when the palaeontology of the whole series comes 

 to be exhaustively studied. 



The Claxby Ironstone as developed at Acre House and Donning- 

 tpn may then be regarded as equivalent to the beds D 1 to D 4, 

 forming the upper part of the ' Zone of Belemnites lateralis ' 

 in the Speeton section ; and the presence of the precursors of a 

 change of the fauna in its topmost clayey layer brings, the 

 stratum into the closest agreement with the Yorkshire beds, where 

 we find the same indications at this horizon in the Compound- 

 Nodule Band, D 1. 



Prom this correlation it follows that the palaeontological affinity 

 of the deposit is altogether with the underlying Spilsby Sandstone, 

 although stratigraphically it seems to be more closely connected 

 with the overlying Tealby Clay. At Nettleton Hill it is clear that 

 the ironstone and associated ferruginous clay extend quite to 

 the top of the zone of Belemnites lateralis. That the striped clay 

 immediately overlying it contains a different fauna is well shown 

 by the following section, recently exposed by a slip in an old 

 quarry, at the second fence south of the old mine-buildings near 

 Acre House : — 



