493 Bihliographical 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 Breissena 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 

 18(54. Its occurrence in tributaries of the Rhine, Mosel, and Main 

 is recorded by Messrs. Noll, Mandel, and Greim (Zoolog. Gart. 

 Frankf. 18G4, 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 

 (Verb. 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 (Verb. ntrf. Ges. Basel, iv. 18G4, 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 



