106 DANFORD : NOTES ON THE SPEETON AMMONITES. 
These last are chiefly of the round-backed kind, and 
generally very fragmentary. Most of them seem to belong to 
0. (Polyptychites) bidichotomus and 0. ( — ) polyptychus, but 
0. ( — ) Beani also occurs, and a very globose form, suggestive 
of 0. ( — ) Keyserlingi, but with ribs finer and more numerous 
than in that species. 
Among the fragments found there are also indications of 
the existence of other alhed forms, some of which must have 
been of considerable size, as part of a whorl of the bidichotomus 
type measured nearly six inches across. 
At this horizon Za^era/i5-Belemnites swarm, most of them 
showing signs of much exposure. There is also a slight sprink- 
ling of Bel. jaculum. Other fossils, such as Pleurotomaria, Pleuro- 
mya, Pecten, Exogyra, &c., are common. Saurian remains 
are not rare,* and there is a good deal of fossilised wood. It 
is, in fact, a heterogeneous collection of materials, somewhat 
resembling that of the Coprolite seam. Though the rest of 
this bed is comparatively poor in fossils, it has yielded interesting 
forms, one an Hoplites, which quite agrees with Sayn's descrip- 
tion and figures of H. Arnoldi, from the beds with Bel. latus 
at Blegiers, Basses Alpes,| which Pavlow says is not the Arnoldi 
of Pictet, and renames heteroptychus. This specimen is in 
the phosphatic state, well preserved, measures 48 mm., and 
has the deep constrictions (4) bordered by more strongly developed 
ribs that are mentioned by Sayn, but not by Pavlow^ in his 
description or apparent in his figures of H. heteroptychus from 
an unknown horizon at Speeton.J In the outer whorls the 
sculpture is irregular, as in these figures, but in the inner the 
umbilical ribs give rise to three, or more frequently four, branches 
which spring from sharply pointed and prominent tubercles, 
* Saurian remains also occur at the top of the Kimeridge and the 
base of the Brunsvicensis zone. 
f " Notes siu* quelques Ammonites nouvelles ou peu Connues du 
Neocomien Inferieur," BulL Soc. Geog. France, Series 3, vol. 17, p. 682,. 
PL XVII., figs. 6, 7. 
+ "Argiles de Speeton," p. 109, PI. XI., fig. 22. 
