The Ammonites

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Abstract
With the exception of certain pyritized ammonites from a few horizons, notably the Tropidoceratids discussed below, the specimens from the Belemnite Marls are not in a good state of preservation. Some, like the Polymorphites of the lineatus type, from Bed 112, or Phricodoceras taylori from the base of the Marls, are not difficult to recognize, even in crushed impressions, while from the occurrence, in Beds 115–118 a , of numerous small pyritized ‘ Uptonia bronni ’ (Rœmer) it may be inferred that the associated traces of larger whorl-fragments belonged to the adult Uptonia jamesoni . The poor state of preservation of the ammonites is all the more regrettable, since certain examples from the comparatively unfossiliferous lower three-quarters of the Marls cannot be definitely identified, even generically. Correlation with other areas where the jamesoni zone is well developed, for instance Pabay or Wurtemberg, cannot thus be more accurately established than in my previous paper (Spath, 1923, p. 6). Of the family Deroceratidæ of the lower beds, Apoderoceras Buckman and Phricodoceras Hyatt are alone definitely recognizable, while Metaderoceras Spath and Hyperderoceras Spath are represented only by imperfect specimens of uncertain affinities. Still more doubtful are the fragments provisionally referred to Tetraspidoceras Spath, and it is possible that at least some of these may belong to the Liparoceratid genus Parinodiceras Trueman. Of the presumed derivatives of Deroceratidæ, Cæloceras Hyatt, on the one hand, is represented by pyritized examples; but the forms of Liparoceras Hyatt, on the other, are badly preserved, as are the specimens of its probable ‘degenerate’

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