52 
POPULAR SCIENCE REVIEW. 
the earth. Geological facts seem also to stand in the way of any such 
assumption. 
As we have already stated, the present volume contains six out of the 
fifty memoirs in which the zoological results of the expedition are to he 
reported upon. There are some of the other memoirs, to the appearance of 
which we look forward with more interest than those here published, from 
the very nature of the objects to be treated of in them, such as the Corals 
and Hydroids, the Echinoderms, the Medusae, the Sponges, &c. ; but we can 
hardly hope to get more finished and complete treatises than those now 
before us. 
The first of them is by Mr. Thomas Davidson on the Brachiopoda collected 
during the voyage ; and when we say that it possesses all the characteristics 
of that gentleman’s well-known work, the reader will understand that it is a 
most valuable contribution to the knowledge of the class of which it treats. 
The number of species obtained was not very great ; indeed, Mr. Davidson 
seems rather disappointed that he had not more materials to work upon. 
There were in all 107 species, and of these comparatively few were from 
great depths. In his remarks on their bathymetrical distribution, Mr. David- 
son shows, indeed, that the Brachiopods constitute but a small element in the 
abyssal fauna, — 57 of the species were procured at a less depth than 100 
fathoms ; and in 125 dredgings down to 600 fathoms they occurred about 25 
times, while in 281 dredgings below 600 fathoms Brachiopods were brought 
up only 16 times. Further we find that 98 species occurred above 500 
fathoms, 16 between 500 and 1000, 6 in the next 500, 4 between 1500 and 
2000, and only 3 between the last-named depth and 2900 fathoms, the deepest 
dredging in which Brachiopoda were obtained. Many species have consider- 
able range in depth, the most striking in this respect being Terebratula vitrea 
from 5 to 1456, Terebratula Wyvillii from 1035 to 2900, and Discina atlan- 
tica from 600 to 2425 fathoms. Before describing the species and important 
varieties of Brachiopoda in the Challenger's collections, Mr. Davidson makes 
some general remarks on the classification of those animals, and gives a most 
valuable tabular list of the known recent species, showing their habitats and 
range in depth, and indicating the species which also occur in the fossil state. 
Ten species have been described as now, and these, with many of the others, 
are figured in four plates drawn, as usual, by Mr. Davidson himself. 
Prof, von Kolliker’s report upon the Pennatulida is scarcely so elaborate 
as the one just referred to ; but it is also of much interest from the large 
number of new forms which the distinguished author has had to make 
known. The total number of species in the collections was 38, belonging to 
exactly half that number of genera ; but of these, 27 species, and 7 generic 
types, are described as new. Further, the new types brought under his 
notice have induced the author to modify his classification of these Polyps 
(proposed in 1872), and he tabulates his new arrangement at the end of his 
paper.* Prof. Kolliker’s memoir is illustrated with eleven plates very nicely 
executed in Germany under his own superintendence. Both the figures and 
the descriptions relate almost entirely to the external characters of the Polyps 
* As this may interest some of our readers, we have reprinted it in a 
slightly altered form in the Scientific Summai'y. 
