434 MR. S. S. BTJCKMAIS' ON" [vol, Ixxviil, 



it may be presumed that he would have appended some less general 

 term. 



On the assumption that at Haselbury the Hammatocerata 

 occupy a higher bed, and are of later date than the Ludwigoids, 

 which would lead to a theory of a Hammatocerate-Erycite horizon 

 as distinct, that is, of later date than that of Ludwigoids, tlie facts 

 of distribution could be explained. In Italy strata of murcliisoncB 

 hemera are absent or only represented in part, but those of a 

 Hainmatocerate-Erycite hemera are present. In the Hebrides, the 

 former was very conspicuous, but there is as yet no evidence for 

 the latter. In Dorset-Somerset the strata of the murcliisonce 

 hemera are developed over a wide area ; but those of the Hammato- 

 cerate date are wholly destroyed in some places, and partly removed 

 in others. At Haselbury a bed assumed to be that of Hammato- 

 cerate date is preserved in sufficient thickness to attract attention 

 as a deposit superior to that yielding ' Ammo7iites murcliisonce' 



More analysis on these ines may suitably come later, and will 

 be of greater value if and when some of the species of Hammato- 

 cerates can be figured. But, meanwhile, it may be advisable to 

 consider the possibility of a Hammatocerate-Erycite date, as inter- 

 mediate between those of murcliisoncE and hradfordensis, and to 

 date Bed 3 of Haselbury in Hudleston's (and Mr. Richardson's) 

 communications as Hammatocerate-Erycite? rather than as ''hrad- 

 fordensis? ' 



The Cotteswold evidence seems in favour of this view. There 

 between the Pea G-rit {miircliisonce hemera) and Oolite Marl 

 {hradfordensis) is a thick mass of poorly fossiliferous, perhaps 

 non-ammonitiferous freestone Avith a more or less eroded surface : 

 this deposit, in part at any rate, and the subsequent erosion 

 (prior to hradfordensis) would mark the time required for laying 

 down a Hammatocerate-Erycite stratum in other areas. 



A short record of the chronological succession and geographical 

 •occurrences of some of the principal Hammatoceratid forms shows 

 -the faunal repetition and the limited extent — in some areas — 

 over which the particular strata have been preserved : it is the 

 earliest of these horizons that has come so much into discussion 

 in connexion with the Watton Bed (see p. 387). 



Table V — Hammatoceratids : Cheonological Succession and 

 Geographical Occuhrence. 



Interv^eniiiG- hemerse omitted. 



Hemerae. Fauna and Localities. 



JEudmetoceras. JEudmetoceras spp.^, Euaptetoceras.^ 



[disciteslconcava]. Bradford Abbas district; Beaminster district 



(Dorset) ; Lago di Garda (Italy). 



' Hammatocerate '-Er^xite. ' Hammafoceras,' JEri/cites,.AbhasHes,^ Amhersites? 

 {hradfordensisjmurchisoncB]. Dorset and Somerset ; Normandy; Lago di Garda : 



Lombardy (Italy) ; Monte Grappa (Italj') ; 



Bakony (Hungary). 



1 I, 8, pis. clxxix, clxxx, ccxcix. 2 i^ g, pi. ccxxxvi. 3 i^ g, pi. ccxxxvii. 



