Mr. J. W. Judd on the Punfield Formation. 77 



Bunter ; and in support of this opinion he cited both stratigraphical 

 and palaeontological evidence. He described what he regarded as 

 the sequence of events during the accumulation of the later Triassic 

 deposits and the passage through the Bhaetic to the Lias, and inti- 

 mated that the same reasoning would apply to other British strata, 

 especially some of those coloured red by oxide of iron, including the 

 Permian, the Old Bed Sandstone, and a part of the Cambrian. 



2. " Note on a large Beptilian Skull from Brooke, Isle of "Wight, 

 probably Dinosaurian, and referable to the genus Iguanodon." By 

 J. W. Hulke, Esq., F.B.S., F.G.S. 



The author stated that the skull described by him was obtained 

 from a Wealden deposit at Brooke, in the Isle of Wight, from which 

 many remains of Dinosauria have been obtained. He described its 

 characters in detail, and remarked that its most striking peculiarities 

 were : — the completeness of the bony brain-case ; the obliteration of 

 the sutures, especially those of the basicranial axis ; the massiveness 

 of the skull ; and the great downward extension of the basisphenoid, 

 with the attendant upward slant of the lower border of the basi- 

 presphenoidal rod. The first of these characters occurs elsewhere 

 among reptiles only in Dicynodon ; and the first and second cha- 

 racters combined were regarded by the author as approximating the 

 skull to the ornithic type. The reference of this skull to Iguanodon 

 was founded chiefly on the place from which it was obtained, which 

 has furnished abundant remains of that genus, and on the oblitera- 

 tion of the sutures, which the author stated to be a character of the 

 mandibles of Iguanodon. 



February 8, 1871. — Joseph Prestwich, Esq., F.B.S., President, 

 in the Chair. 



The following communications were read : — 



1. " On the Punfield Formation." By John W. Judd, Esq., F.G.S., 

 of the Geological Survey of England and Wales. 



Those formations which have been deposited under fluvio-marzne 

 conditions, and which yield at the same time marine, freshwater, 

 and terrestrial fossils, are of especial interest to the geologist, as 

 they furnish him with a means of correlating the great freshwater 

 systems of strata with those of marine origin. 



At the bottom of the Wealden we have one such fluvio-marine 

 series, the well-known Purbeck formation ; at its summit is another, 

 less known, but not less important, for which the name of " Pun- 

 field Formation" is now suggested. Some of the fossils of the latter 

 were first brought under the notice of geologists by Mr. Godwin- 

 Austen in 1850 ; and their peculiarities have since been the subject 

 of remark by Prof. E. Forbes, Sir C. Lyell, and others. 



The typical section of the beds is at Punfield Cove, in the Isle of 

 Purbeck, where they are about 160 feet thick, and include several 

 bands with marine shells. The lowest and most remarkable of these 

 yields about forty well-defined species, many of which, as well as 



