NOTES ON THE SPEETON AMMONITES. 



C. G. DANFORD. 



A RESIDENCE of Several j'ears in the neijj;"hbourhood of Speeton 

 has enabled the author to collect many fossils from the clays and 

 shales underlying" the Chalk. With regard to the Amnwtii/ichr, 

 his results confirm the general succession given by Pavlow and 

 Lamplug-h, and add some further information. 



The lowest portion of the Kimeridge clay w^hich the author 

 has been able to examine in exposures on the shore contains 

 numbers of ill-preserved ammonites of the square-backed 

 Hoplites group ; while the higher part contains forms of a 

 different type, belonging to the round-backed Perisphinctes and 

 allied genera. 



In the lower part of the zone of Bclemnilcs lateralis 

 ammonites are extremely rare, and the author has no fresh 

 information to offer ; but in the upper part they become plentiful. 

 The very globose forms of Olcostephaniis {Olc. gravcsiformis^ 

 keserlingi^ etc.) occur mainly in the bed D 3 of Mr. Lamplugh's 

 classification, but are usually in bad preservation. The over- 

 lying bed, D 2, is perhaps the most interesting of the whole 

 series ; at its base both the Olcostcphani and the Hoplites are 

 very numerous, the former being often in the condition of 

 imperfect phosphatic casts. Above this band the round-backed 

 ammonites entirel}' disappear, though Belemnites lateralis con- 

 tinue to be fairly abundant up to D i. 



It therefore appears that the southern Hoplites obtained full 

 possession of the area earlier than their associated southern 

 belemnites oi \\\q jactilian type, although rare examples of these 

 belemnites occur in the clays below D 2. 



The lower part of the zone of Belemnites jacnlum, besides 

 yielding many Hoplites, contains occasional ammonites per- 

 taining to the genera Holcodiscns and Astieria (of the Olco- 

 stephani), and also to other genera. The higher beds are 

 occupied b)' Olcostephani of the genus Simbirskites, biit these 

 beds have of late years been so poorly exposed that no further 

 information can be given regarding the distribution of these 

 forms. 



In the zone of Belemnites bransvicensis ammonites only occur 

 at the extreme base, where there are a few examples of one of 

 the Simbirskites, and in its uppermost beds, where the g-enus 

 //opliteSy represented by //. desltavesi, reappears associated with 



A paper read to Sfctioii C oCtlic Mct-tiiii;' ottlu- Hrilisli Associalioii, ^'l)|•k. 



Naturalist, 



