492 Bibliographical Notice. 
justice to say that they have conscientiously, honestly, and ably dis- 
charged a most difficult task. 
On a previous occasion we pointed out to our readers that it is 
impossible this work can be continued unless it be upheld by a large 
amount of support. Its publication is necessarily very costly ; and 
an extensive sale is required to prevent a heavy loss falling upon 
that most enterprising of publishers, Mr. Van Voorst, from whose 
publications natural history has already received so great an im- 
petus in this country. We cannot too strongly again insist upon 
the fact that it is the duty of every person interested in science, who 
can possibly afford to do so, to purchase the ‘ Record.’ Dr. Giinther 
and Mr. Van Voorst have commenced this annual solely in the inter- 
est of the progress of zoology; it remains for others, by their sup- 
port, to enable them to continue it. The real student requires no 
instigation to purchase a book which he cannot do without, and the 
continued publication of which he knows to be of the greatest im- 
portance to himself; but, alas! the real scientific workers are few 
in number, and a sale among them alone would not suffice to prevent 
a heavy loss falling on the publisher, which would, of course, neces- 
sitate the discontinuance of the work. Let every friend of science, 
then, come forward and support the ‘ Record.’ 
It will give some idea of the character of the summaries of papers 
in the ‘ Record,’ if we conclude this notice by giving an example. 
We shall select for this purpose what is told us in the two volumes 
on the migration of the mollusk Dreissena polymorpha. There are 
two mollusca, the steady diffusion of which has been the subject of 
most interesting and careful investigation for many years past. One 
of these, a marine Gastropod, is Lottia testudinalis, of which the 
gradual migration southwards down the eastern and western coasts 
of Great Britain has been clearly and distinctly traced. The other 
is one of the Acephala, Dreissena polymorpha. This is a freshwater 
species, nearly allied to the Mussel, which is rapidly spreading 
itself throughout the rivers and canals of this country, as well as 
those of the continent of Europe. The first volume of the ‘ Record’ 
supplies us with the following particulars :— 
“The immigration of Dreissena polymorpha into parts of Europe 
where it was originally unknown, has continued during the year 
1864. Its occurrence in tributaries of the Rhine, Mosel, and Main 
is recorded by Messrs. Noll, Mandel, and Greim (Zoolog. Gart. 
Frankf. 1864, pp. 30, 89, and 124), with the addition of the dates of 
its first detection (1855-61); its presence in the middle part of the 
Rhine, at Knielingen near Carlsruhe, is testified by Hr. Kreglinger 
(Verh. ntrw. Verein. Karlsr. vol. i.); its appearance higher up in the 
Rhine, near Huningue, where it was found by Hr. Seul, is announced 
by Hr. P. Merian (Verh. ntrf. Ges. Basel, iv. 1864, p. 94); and, 
finally, its immigration into the Loire near Orleans, by way of 
canals, in 1864, has been observed by Capt. Morlet (Journ. Conch. 
pp. 309-314). Towards the end of last year the Recorder” (Dr. E. 
von Martens) “collected all the facts and observations concerning 
the immigration (or rather importation) of this mollusk which had 
