520 Notices of Memoirs — C. G. Danford — Speeton Ammonites. 



The author considers the Bunter to be fluviatile rather than 

 lacustrine deposits, chiefly formed by large rivers. Two of these 

 flowed from a mountain region, of which Scotland and the extreme 

 north of Ireland are fragments, and a third from a similar region to 

 the south-west of Britain. Deposits comparable with the Bunter, 

 and especially the pebble-bed, may be found on the border of the 

 Alps, and these rivers prol)ably traversed (at any rate, early and late 

 in the Bunter epoch) arid lowlands, from which, if not absorbed, they 

 may have escaped by some channel now buried under south-eastern 

 England. The Keuper sandstones, as he shows, indicate the setting 

 in of inland sea conditions, the Red Marls being generally regarded 

 as deposited in a great salt lake. These, like the clays of the 

 Jurassic system, were probably derived from the mountain ranges, 

 which had previously supplied sand and pebbles. 



In fact, the physical and climatal conditions of the Trias — and the 

 same perhaps may also be said of the Permian — were probably to 

 some extent comparable with those now existing in certain of the 

 more central parts of Asia, such as Persia or Turkestan. 



V. — Notes on the Speeton Ammonites. By C. G. Danford. 



A RESIDENCE of several years in the neighbourhood of Speeton 

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

 shales underlying the Chalk. With regard to the Ammonitidge, his 

 results confirm the general succession given by Paviowand Lamplugh, 

 and add some further information. 



The lowest portion of the Kimmeridge Clay which the author has 

 been able to examine in exposures on the shore contains numbers of 

 ill-preserved ammotiites 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 Belemnites lateralis Ammonites are 

 extremely rare, and the author has no fresh information to off'er ; 

 but in the upper part they become plentiful. The very globose 

 forms of Olcostephanus (0. grnvesiformis, Keyserlingi, etc.) occur 

 mainly in the bed D 3 of Mr. Lamplugh's classification, but are 

 usually in bad preservation. The overlying bed, D 2, is perhaps 

 the most interesting of the whole series ; at its base both the 

 Olcostephani and the HopJites are very numerous, the former being 

 often in the condition of imperfect phosphatic casts. Above this 

 band the round-backed Ammonites entirely disappear, though 

 Belemnites lateralis continues to be fairly abundant up to D 1. 



It therefore appears that the southern Hoplites obtained full 

 possession of the area earlier than their associated southern Belemnites 

 of \\\Q jaculum type, although rare examples of these Belemnites occur 

 in the clays below D 2. 



The lower part of the zone of Belemnites jaculum, besides j'ielding 

 many Hoplites, contains occasional Ammonites pertaining to the 

 genera Solcodiscus and Astieria (of the Olcostephani), and also to 

 other genera. The higher beds are occupied by Olcostephani of the 



