O14 Reports and Proceedings— 
arranged to show the relations of the species to one another by inter- 
mediate connecting forms. In this way the passage of Terebratula 
Cantabrigiensis through T. depressa, T. Seeleyi, and T. prelonga to T. 
microtrema, is said to be simple and clear. In the same way various 
species of Waldheimia and also of Terebratella have been shown to 
graduate one into the other. These are very important and interest- 
ing facts, and in reference to them the author says, ‘“* While thus 
pointing out the mutability of the forms of Brachiopoda, it is perhaps 
worth while observing that the value of the species is thereby in 
no way decreased, but on the other hand is, I believe, considerably 
increased both to the Naturalist and Stratigraphist. Whether we call 
our various forms varieties, races, types, or any other name, the facts 
of the great constancy of our recognized ‘specific ” types, and their 
limited distribution in space and time still remain to us: our charac- 
teristic species are as useful as ever they were; while on the other 
hand we shall have added a most important help to the determination 
of the relations of rock beds to one another when we can recognize 
the true meaning of allied genera, species and varieties.” 
Turning to the account of the derived fossils, we learn that most 
of them are preserved in phosphate of lime, and that they belong 
to various ages ranging from the Neocomian to the Oxford Clay. 
The occurrence of the Neocomian species Ammonites Deshayesi, 
Thetis minor, Terebratula ovoides, etc., as derived specimens, is con- 
sidered very remarkable. The bed from which these fossils were 
obtained seems to be represented in the Hast of England by large 
boulders of Neocomian grit, perhaps closely connected with the 
Lower Neocomian Sands of Lincolnshire. 
There is an interesting chapter on the relations of the Upware 
and Brickhill deposits to other British formations, and a chapter on 
the Foreign relations of the Beds. These conclude the first part of 
the book: the second part-is devoted to “special paleontology,” or 
a description of the fossils, including many new species, and this 
portion of the work is illustrated by eight well-executed plates. 
The author is assuredly to be congratulated upon the success of his 
labours, resulting in the many new and interesting facts here brought 
together, which must have required much labour and patient investi- 
gation in their collection and solution. H.B.W. 
7? OR TS ALD) G2 OC aD ae 
————~——_—_ 
GEOLOGICAL Socrety oF Lonpon. 
I.—June 6, 1883.—J. W. Hulke, Esq., F.R.S., President, in the 
Chair.—The following communications were read :— 
1. ‘‘The Estuaries of the Severn and its Tributaries, an inquiry 
into the Nature and Origin of their Tidal Sediment and Alluvial 
Flats.” By Prof. W. J. Sollas, M.A., F.R.S.E., F.G.S. . 
Various sources have been ascribed to the mud which is so charac- 
teristic of the estuaries of the Severn and its tributaries, such as the 
rivers themselves, the waste of mud shoals, or of bordering cliffs, 
