PREFACE. ix 
have been most difficult and laborious, but with regard to 
many rare and inaccessible publications it would have been 
impossible. The list furnished by M. Agassiz is therefore 
substantially produced here, but it has undergone a great 
amount of careful revision and correction. Several thousand 
additional titles, selected with great care, have also been 
added, either by myself or under my immediate inspection. 
These are principally extracted from British scientific perio- 
dicals, with whose contents continental naturalists are too 
imperfectly acquainted. Many of these titles had been already 
extracted at second-hand by M. Agassiz from French and 
German journals where they are translated, and the works 
of many British writers consequently‘ appeared in a foreign 
dress. In such cases the original English title has been sub- 
stituted, and a reference made to the foreign work where the 
translation appears. In some instances however I have not 
had an opportunity of verifying such titles with the originals, 
and they consequently still remain in the list in their exotic 
form. 
In the case of very short or unimportant communications, 
a certain amount of discretionary power was indispensable. 
Our popular “ Magazines” of Natural History teem with tri- 
fling notices, often anonymous, sometimes brief and indefi- 
nite, sometimes wordy and inflated, but which do not contain 
a single fact of scientific importance. To have recorded all 
such in our list would have added bulk but not value, and 
they have therefore been in general omitted. But I have 
always endeavoured to render due justice to every properly 
authenticated statement, however brief, of a new or import- 
ant observation in Zoology or Geology. 
Wherever it has been practicable, the lists of each author’s 
writings have been forwarded to him for correction before 
sending them to the press, and the works of living British 
