40 Reviews—T. Roberts —Jurassic Rocks, Cambridge. 
who might be ready to assist, would be prepared to undertake the 
responsibility of publication. Authors may do their work as a 
labour of love ; but publishers are usually animated by other motives. 
We must however state, that the issue of the Catalogue of Vertebrata, 
to which we have referred, owes much to the enterprise of the Pub- 
lishers, Messrs. Dulau & Co. We fear that their laudable efforts 
have been attended by loss. In the present instance we believe the 
authors have undertaken the entire cost of publication. Geologists 
should bear this in mind, and even if they are not specially interested 
in Vertebrata and Jurassic Gasteropoda, they should cheerfully and 
readily support the undertaking, for only by so doing can the great 
work of cataloguing our British Fossils be successfully accomplished. 
IJ.—Tue Jurassic Rocks or tan NerGHBouRHOOD OF CAMBRIDGE. 
By the late Tuomas Roperts, M.A., F.G.S.  8vo. pp. 96. 
(Cambridge: at the University Press. London: C. J. Clay and 
Sons, 1892.) Price 8s. 6d. 
tle oe work, which has been carefully edited by Mr. Henry Woods, 
serves as a fitting memorial of the labours of its author among 
the Jurassic rocks of the eastern-midland counties. It formed the 
subject of the Sedgwick Prize Hssay for 1886, and has since been 
to some extent amplified; but the author, who had hoped still 
further to extend its scope, unfortunately did not live to see the 
accomplishment of this task. 
The strata to which attention was directed are those from the 
Oxford Clay to the Kimeridge Clay, inclusive; and the main 
questions to be worked out related to the limits of the intervening 
Corallian division. A good deal of work was done, many years ago, 
by Prof. Seeley, and further information was gathered by Prof. 
Blake, Mr. Hudleston, and others; to whose labours and to those of 
other geologists due credit is given. Much remained to be done in 
working out the paleontological horizons or zones in this essentially 
argillaceous series of strata, for rock-beds are only occasionally 
developed, as at Upware, Elsworth, and St. Ives. To this work 
Mr. Roberts devoted especial attention, and most valuable results 
have followed. 
In the Oxford Clay of the district he recognizes three well-marked 
zones, in ascending order, as follows (the figures should have been 
reversed) :— 
3. Ammonites Duncani and A. Jason (the Ornati group of Am- 
monites) of St. Neot’s. 
2. Waldheimia impressa, at the base of the St. Ives clay-pit. 
1. Ammonites perarmatus, A. crenatus and A. oculatus, and the 
Cordati group of Ammonites, of the St. Ives clay-pit. 
No beds so old as the Kellaways division of Wiltshire (zone of 
Ammonites calloviensis), are anywhere exposed. The fossils of the 
higher beds accord well with those known in other areas, but we 
question whether the zone of Waldheimia impressa can be regarded 
as more than a local sub-zone. It is noteworthy that Ammonites 
Lamberti, which occurs at this horizon elsewhere, and is sometimes 
