170 me. c. Thompson on the [June 1 913, 



Clays (Lower Cretaceous) have yielded abundant material to the 

 Glacial ice, so that Mr. Morfitt has been able to gather a beautiful 

 set of those remarkable globose forms which distinguish the 

 Valanginian fauna, and are so rarely found in place at Speeton. 



A point of much importance in connexion with these fossils 

 from the Drift is that, when one examines the matrices of many of 

 them, it is seen that the rock cannot be now matched within the 

 borders of our county, aud the pertinent question arises : "Whence 

 have they been transported? 



I dealt briefly with the subject in a preliminary note and list 

 published in the Transactions of the Hull Geological Society for 

 1910 ; but in the present paper I propose to offer a more compre- 

 hensive and up-to-date account, in which are included the results 

 of my later researches and of my examination of all available 

 specimens in the possession of other collectors and in the various 

 museums. The net result is that the previous list of ammonites 

 has been more than doubled in these last two years. 



II. The Liassic Ammonites, etc. from the Drift, and their 

 Matrices. 



Planorbis and lower (?) Beds. 



Taking species in their recognized stratigraphical order, the 

 first on the list is Psiloceras (?) Tiagenowi (Dunker, Quenst.). My 

 colleague obtained several specimens from a block of very fine- 

 grained, hard, splintery, ferruginous limestone. These specimens 

 were the first representatives of the species to be recognized from 

 an English source. Mr. Buckman confirmed my determination, 

 aud has since found two specimens in the Tate & Blake Collection 

 at the Museum of Practical Geology, Jermyn Street. This species 

 is a remarkable one, for it has well-defined ceratite suture-lines, 

 with smooth rounded saddles and but slightly corrugated lobes. 

 The rock may actually be a relic of the marine Trias, or may be 

 from some passage-bed not developed, or at any rate not yet found, 

 on land in this country. The species occurs on the Continent in 

 Northern Germany, Bohemia, the North-Eastern Alps, and Switzer- 

 land. So recently as last August another fragment of this species 

 was seen on the face of a block of the same kind of limestone, 

 several miles from the place where the first was found. There 

 is no matrix known at present in the English Trias, or in the 

 Yorkshire Lowest Lias, resembling this. 



Most of the English lists, if not all, give two species of ammo- 

 nites only — Psiloceras jilanorbis and Caloceras johnstoni — as being 

 found in the Planorbis Zone. This restriction is remarkable, for 

 in all the other zones of the Lias there are many representative 

 species of the ammonite race. 



That it is not true of the beds of this zone laid under contribu- 

 tion by the ice-sheet is shown by the fact that, from the many 



