52 TYPE AMMONITES— III Sept. 



This Ammonite-fauna of the Fullers' Earth Rock-Great Oolite 

 strata is the one short and not over-populous break in the remarkable 

 dearth of Ammonites which characterizes — in Great Britain and North 

 France, at any rate — the interval of hemera? post-zigzag to pre-macro- 

 cephalus : a dearth all the more remarkable from contrast with the 

 exceeding richness in Ammonites of the many preceding and succeeding 

 Ages. This period of Ammonite poverty points to considerable 

 geographical change — more or less it is synchronous with estuarine 

 conditions in East England and in Scotland. But this poverty may 

 not be wholly original : it may have been heightened by wide-spread 

 destruction of ammonitiferous deposits. 



The robust character of the genera of the Tulitida?, their somewhat 

 nautiloid shape, poverty of ornament and rather simple suture-line 

 suggest that they are deep-sea forms which, at any rate in the case of 

 Tulites of the Minchinhampton Shelly Beds, have drifted into a shallow 

 water deposit, bearing traces of their journey in the condition of their 

 tests. The Tulitidae are a stock of Coronati, less developed than their 

 predecessors of the Bajocian. The biological order of the genera is 

 somewhat that in which they have now been described, certainly 'Tulites 

 is least, and Sphceromorphites is most changed from the original stock. 

 This biological order is not in accordance with their geological succession ; 

 but a more changed series is sometimes the first to arrive in a new area ; 

 to be followed later by its less changed cousins, not necessarily in order. 



Addendum : A Tulitid has been sent by Mr. J. Pringle, F.G.S., 

 from Oxfordshire : it falls between Madarites calvus and M. pravus, 

 see p. 46. 



Madarites glabretus, n. " Teloceras siibcontt -actum." [Cadicone 

 to] incipient serpenticone, only outer whorl preserved, body-chamber 

 (cast) just short of a whorl in length, finished by 'plain mouth and no 

 constriction. No ornament. Geol. Surv. Engl., No. PL 866 ; from 

 Railway " cutting between Bucknell and Ardley Wood," N.W. of 

 Bicester, Oxfordshire, " found loose, probably from Bed 31, Fullers' 

 Earth Rock, of Mr. M. Odling, F.G.S. (Quart. Journ. Geol. Soc, LXIX, 

 1913, p. 490), who quotes Teloceras subcontr actum from this bed " (Mr. 

 J. Pringle) : matrix hard, grey, non-oolitic stone ; S. 79, 38, 59*5, (34 ?) ; 

 *°7< 37 > 4°'5» 36'5 '• max. 116, somewhat ellipticone. 



According to the statements of the quarry foreman, during opera- 

 tions subject to the making of the line, a large Ammonite was obtained 

 from Bed 26 (Odling), that is 4 beds, or about 6 feet above Bed 31 : 

 it was handed over to an official of the Great Western Railway. The 

 damaged impression which the foreman showed to Mr. Pringle and 

 myself suggested some relative of what is now named Bullatimorphiles, 

 but much larger — some 10-12 inches (250-300 mm.) — than anything 

 known at present from Great Oolite-Fullers' Earth Rock strata. Mr. 

 Pringle's attempts to trace the whereabouts of this specimen were not 

 successful ; but it is to be hoped that it may be found. 



If the suggested relationship be correct, Bed 26 may be of Bitllati- 

 morphites date, and if Bed 31 be of Madarites date, as there is good reason 

 to think, then Bed 28 is left as, possibly, of the date of Morrisites. The 

 beds superior to Bed 26, up to, say, Bed 21, are, therefore, possibly 

 of the date of Tulites and Morrisiceras — that is, synchronous with part 

 of the Minchinhampton Shelly Beds. Bed 31 of Ardley, 4 feet thick, 

 could contain all the Ammonite horizons ascribed to the Thornford 

 Beds, for, at Troll, they are not much thicker. 



