452 INFERIOR OOLITE AMMONITES. 



Continent. In fact, in the Concawim-bed this country possesses what is almost an 

 unique deposit — a development of strata which, so far as is known at present, 

 cannot, in its entirety, be matched elsewhere. In Normandy the Concavum-bed 

 has often been entirely, or to a great extent, destroyed by contemporaneous 

 erosion, 1 and in this country it is absent from many places. It would appear 

 that it is absent or has been destroyed over the greater part of Europe. It will be 

 necessary to know whether it has been destroyed or whether it was not deposited, 

 or if deposited whether it contains Sonninise. Present evidence seems to point to 

 the fact that the Sonninise came from the west and settled first in the Anglo- 

 Parisian basin. Munier-Chalmas has just announced the discovery of Sonninise 

 in the Murchisonse-zone of Normandy ; 2 and, if this prove correct, the Sonninise. 

 settled in Normandy before they came to this country. They arrived in this 

 country during the Concavi hemera, and would appear to have made Dorset 

 their headquarters, but the curious thing is that they did not arrive in Wiirttem- 

 berg until considerably later, — in fact, using the term which I have lately suggested 

 for geological chronology, their arrival in Wiirttemberg was later by two hemerae 

 than their arrival in Dorset. If the westerly faunal migration of the Sonninise 

 prove to be a fact, it will be in striking contrast to what obtained among 

 Ammonites generally, and especially among the externally similar Hammatocerata. 

 They are found in greater abundance in the north of Italy (Garda See) and along 

 the borders of the Mediterranean, in strata presumably equal (according to 

 Haug 3 ) to our Concavum-Murchisonse-zones, than they are with us. In fact, the 

 Hammatocerata appear to have moved eastwards. Further biological information 

 concerning those species will be given later, when it is hoped that our knowledge 

 of these matters will be more precise than it is now. It is impossible, however, 

 to resist this opportunity of pointing out that only by a minute analysis of the 

 fauna and the distribution of species in time, after the plan which the hemeral 

 system is designed for, can we hope to be able to discover and, what is more 

 important, to express the interesting biological results which the study of faunal 

 migration should yield to us. 



Postscript. — Since the above was sent to the printer I have received, by the 

 kindness of Mr. W. Moricke, his interesting pamphlet entitled ' Versteinerungen 

 des Lias und Unteroolith von Chile.' * Herein are figured two species of Sonninia, 



1 Munier-Chalmas, " L'Etude preliminaire des terrains jurassiques de Normandie," ' Compte rendu 

 sommaire des Seances de la Societe Geologique de France,' No. 14, p. clxv, 1892. 



2 Op. cit., p. clxiv. It is possible that they may be species of Ilammatoceras. 



3 " Sur l'etage Aalenien," ibid., p. clxxvi. 



4 " Beitrage zur Geologie und Palaeontologie von Sudamerika, — Unter Mitwirkung von Fach- 



