1866. | The Progress of Zoology. 51 
Reeves’ magnificent “ Conchologia Iconica.” The number of species 
of Mollusca recently described as new, but without indication of 
their habitat, is fortunately not large, so that our knowledge of the 
geographical distribution of the Mollusca is also advanced by most of 
these papers, especially by those in which an enumeration of all the 
species found in the same district is added. ‘The faunas of Eastern 
Asia and Australia have been more particularly enriched during the 
past year. The systematic arrangement has not been essentially 
changed, but a considerable number of new genera (perhaps rather 
too many) have been introduced into science. The Cephalopoda 
and Pteropoda appear to have been entirely neglected. ‘The Nudi- 
branchiata have been well illustrated with new South American 
species, by Mr. Angas, and by the publication, by Messrs. Alder and 
Hancock, of the beautiful series collected by Mr. Walter Elliot, at 
Waltar, in the Madras Presidency ; but the great mass of observa- 
tions collected upon the Mollusca refer to the Gasteropoda. 
The Tunicata and Polyzoa (Molluscoida) chronicled by Mr. J. 
Reay Greene, are chiefly illustrated by Dr. J. D. Macdonald and Mr. 
Alder, respectively. Dr. MacDonald is of opinion that the Mollus- 
coida and Coelenterata together form an unbroken series of animals 
to be placed between the Mollusca proper on the one hand, and the 
Protozoa on the other. The members of the group thus constituted, 
though developed from true ova, are prone to form compound 
organisms by continuous gemmation. In all, the movement of the 
circulatory fluid is effected either by ciliary action, or by a propulsive 
organ unfurnished with valves. Thus, starting from the Ctenophora 
(Beroé) as a central group, we proceed in two directions towards the 
Molluscoid or higher, and the Ccelenterata or lower, divisions of 
the series. 
Mr. Spence Bate’s Chronicle of the Literature of the Crustacea 
for 1864, enters, perhaps, more fully than any other into debated 
questions and interesting points of detail, and his summary of Fritz 
Miiller’s memoir on behalf of the Darwinian theory on carcino- 
logical grounds, is valuable. The principle of Miller is that the 
surest way to prove the correctness of Darwin’s views would be 
to apply them to a particular group of animals, going as much 
as possible into detail. Such an attempt to set up one common 
pedigree, whether for the families of a class, or the genera of a 
large family, or for the species of a rich genus, and to trace out 
as clearly and comprehensively as possible their common origin, 
might either lead to contradictions in the theory which would 
demonstrate its error, or the theory might throw hght upon 
the succession in which the various circles separated from the 
common type and from each other; or thirdly, although the experi- 
ment might fail, yet should it succeed, it would, from its indepen- 
dent and perfect character, be considered evidence of real value ; 
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