200 ME. G. W. LAMPLTTGH ON THE SPEETON SERIES [May 1 896, 



The cephalopoda are decidedly less abundant than the lamelli- 

 branchiata, but fortunately are still sufficiently numerous and charac- 

 teristic to provide safe grounds for the correlation. The belemnites 

 are widely, though scantily, distributed, and all the specimens yet 

 discovered are of the lateralis-type (Belemnites eocplanatoides, Pavl. ; 

 B. lateralis, Phill. ; B. russiensis, d'Orb.), forms occurring in the 

 lower part of Zone D at Speeton. 



The ammonites, though less rare, are not, as a rule, well pre- 

 served. They have been referred by English palaeontologists to 

 various speeies of obscure antecedents, such as Ammonites plicom- 

 phalus* Sby. ; A. mutabilis, Sby. ; A. Kcenigii, Sby. ; A. rotundus, 

 Sby. ; all names more or less vaguely applied in England, but 

 usually to Jurassic forms. More recently Pavlow 2 has identified, 

 among other species, Olcostephanus (Craspedites) subditiiSfTTautsch., 

 a well-known Continental form of great value in the correlation. 

 At Speeton the corresponding horizon appears to be found in beds 5, 

 6, and 7 of Zone D. These are almost devoid of identifiable am- 

 monites, 3 but the correlation is, I think, well established by the 

 belemnites, combined with the evidence of the overlying and under- 

 lying strata. I have no doubt that, when the remaining branches 

 of the fauna have been more thoroughly studied, a relatively large 

 number of the species will be found to be common to the two 

 areas. 



It is very probable, however, as will presently appear, that the 

 upper boundary of the Spilsby Sandstone is not everywhere of 

 exactly the same age, the accumulation of sandy material having 

 persisted longer in some localities than in others. 



e. The Claxby Ironstone. 



The paucity of sections in the Lincolnshire area is especially 

 detrimental when we attempt to deal with this deposit and the 

 overlying Tealby Clay. In the neighbourhood of Caistor, and for 



1 As illustrating some of the difficulties of the palaeontology it may be 

 noted that, of Sowerby's two types of Ammonites plicomphalus now preserved in 

 the Natural History Museum, one is labelled as from ' Kelloway Eock, Boling- 

 broke,' and the other ' Kimeridge Clay.' Both are in a matrix of Spilsby Sand- 

 stone. In all the collections, fossils from the different horizons in Lincolnshh*e 

 are much mixed. 



2 ' Argiles de Speeton,' p.116 (sep. copy). 



3 In collecting from the 'Pale Beds' (D6) at Speeton I hare obtained 

 curious evidence of the former existence of large ammonites at this horizon. 

 Full-grown Exogyrce (sinuata, var. cf. Couloni) are of common occurrence, 

 and one of these presented on one surface an excellent cast of a segment of 

 the interior whorls and ribs of a large ammonite, to which the oyster had 

 evidently been affixed. The cast is insufficient for specific determination, but 

 shows clearly that the ammonite has not been of the deep-whorled Polypty- 

 chites-type such as tenant the o\ erlying beds, but may have been akin to the 

 Craspedites-grouip of Olcostephani. 



