422 
Bibliographical Notice . 
sponges which are fundamentally different in the nature of their 
skeleton and in other respects, so that it would be quite impossible 
to classify them on this principle ? 
The discovery by Prof. C. Stewart of the rudimentary sense- 
organs or palpocils in sponges is referred to ; but Dr. Lendenfeld 
claims that he was the first to describe these organs in sponges, and 
that he jras discovered various modifications of a nervous system in 
horny as well as in calcisponges. An unimportant objection is made 
to the terra 44 palpocil ” for these organs ; but the new one proposed 
seems hardly necessary. The stratification or layers noticeable in 
the horny fibres of sponges is attributed to the variable character 
of the spongin produced by the spongoblasts or fibre-cells at different 
intervals owing to changes in outer circumstances, and the produc- 
tion of pith in the fibres of the Hexaceratina is considered to be due 
to the action of cells which eat out the fibres and change the spongin 
into pith ; but this theory has been called in question by Polejaeff, 
who considers the pith to be an original constituent of the fibres. 
Regarding the physiology of sponges, the somewhat humiliating 
confession is made that we do not yet know the kind of food which 
is taken by them, nor how it is absorbed, nor the particular way in 
which the functions of secretion and respiration are carried on ; and, 
further, but little is as yet definitely known of the embryology of 
horny sponges. As to the phytogeny of horny sponges, the author 
concludes that they have originated from four distinct phyla, which 
have been developed independently of each other from as many 
different groups of siliceous sponges. The system of the horny 
sponges set forth in this work is stated to be entirely new and fun- 
damentally different from any previously propounded. The two 
concluding chapters deal with the phytogeny and systematic position 
of sponges generally, and the inevitable ancestral tree is produced 
— we are told for the first time — showing the relationship of the 
different families of the class. The author considers that the phylo- 
genetic affinities of sponges are now established on a satisfactory 
footing, and the merit of this is modestly ascribed to four recent 
writers of the 4 Challenger ’ Reports on these organisms and to the 
author himself. 
Apart from hypothetical subjects, no doubt can be entertained of 
the value of this Monograph, as giving us for the first time full, 
detailed, and accurate descriptions of the minute anatomy and other 
structural characters of the group of horny sponges, so that in future 
there should be no serious difficulty in determining any member of 
it. Serious exception may be taken, however, to the arbitrary way 
in which, in many instances, the generic and specific names given 
by previous authors to many of these sponges have been disregarded 
and set aside by Dr. Lendenfeld in favour of new terms proposed by 
himself. It is indeed asserted that the sense in which the terms 
44 variety,” 44 species,” and 44 genus” are used is the result of the 
author s own original researches and independent of any authority, 
and further that it is impossible to give a definition of his own 
peculiar meaning of them ; but such a plea will not excuse the 
autocratic way in which new names are proposed by which previous 
