IV 
rEEFACE. 
The variation in their forms, and the number both of genera and 
species in the Palseozoic rocks, attest the long lapse of ages which 
this period represents ; their rapid diminution in the Neozoic 
period, both in numbers and variation of form, bespeaks the dying- 
out of this ancient and once dominant type. 
The chapter at the close of this volume on “ Ehyncholites,” or 
mandibles of Nautili, will prove very useful to palaeontologists. 
These bodies are so often found separately in rocks dissociated from 
the other remains of the auimal of which they once formed a part 
that their true species cannot readily be determined ; yet in a few 
instances they occur within the body-chamber of the animal’s shell, 
and so can be identified with certainty, as in the case of Nautihoi 
Libanoticus (p. 371). 
Mr. Foord’s excellent figures (drawn by himself) greatly enhance 
the value of this Catalogue, which, with its ample bibliographical 
references, deserves to find a place in every scientific library. 
HENRY WOODWARD. 
British Museum (N. H.), 
Department of Geology, 
February 12th, 1891. 
