222 Bibhographical Notice. 
groups; twenty more pages would have sufficed for this, and the 
usefulness of the book to students would have been immensely in- 
creased. 
Out of the 248 pages of which this volume is composed, the actual 
catalogue of species, including the descriptions, occupies 193; the 
remainder is devoted to a brief introductory chapter, a tabular and 
a stratigraphiecal list of species, a bibliography, and a copious index. 
The introduction treats very briefly of a few general matters con- 
nected with fossil sponges and their mode of occurrence, and deals 
especially with those curious phenomena of fossilization involving 
the replacement of silica by carbonate of lime and vice versd, about 
which there has been considerable discussion of late years. This 
introductory portion concludes with a few remarks upon the geolo- 
gical distribution of sponges, and on the classification of the fossil 
forms, with a classified list of the orders, families, and genera re- 
ferred to in the body of the work. The tabular list of species, in 
which those occurring in Britain are specially indicated by an 
appended asterisk, shows in vertical columns the distribution of the 
species in the broader divisions of geological time ; while the strati- 
graphical list displays the same series of facts arranged from a geo- 
logical point of view. This latter list brings into promimence a 
remarkable point, namely, that the earliest sponges of all, the 
Cambrian Protospongia fenestrata and the three species recorded 
from Dr. Hicks’s Ordovian strata, all belong to the Hexactinellidee, 
which have commonly been regarded as the most complex of sponges. 
Further it would appear that while the Cretaceous deposits swarm 
with the remains of these organisms, they are represented far more 
scantily in the Tertiary deposits. The British Museum collection 
possesses only some forms of Cliona from the Tertiaries. 
We trust that it will be very clearly seen from this short notice 
that Dr. Hinde, in this Catalogue, has furnished his confréres with 
a most valuable treatise ; in fact, with this work and those of Prof. 
Zittel already referred to, the Sponges, from a literary point of 
view, may be regarded as perhaps the most favoured group of fossil 
organisms. But we have yet to say a few words about the plates 
with which the volume is illustrated, as these contribute in no small 
degree to its usefulness and importance. There are no fewer than 
thirty-eight of these plates, and they are for the most part beauti- 
fully executed, showing in a most characteristic fashion the external 
appearance of the fossils, with many of which one is tolerably 
familiar, and also the spicular and other structural characters known 
chiefly to students of the group. ‘These illustrations, which by their 
beauty and number admirably illustrate the text and help to render | 
this the finest paleeontological treatise that has issued from the { 
English press for many years, reflect the highest credit upon the 
artists concerned in their production—a credit, however, which they | 
must be content to share with the author, as in such a case as this 
we may be pretty sure that without the most careful superinter 
dence on his part, such excellent results as we here meet with cout ° 
not have been attained. ¥ 
