REVIEWS AND BOOK NOTICES. 415 
sea-urchin is the Pourtalésia, first found by Pourtalés off the coast 
of Florida. The British dredgers have revealed a second species 
(P. Jeffreysii W. Thomp., Fig. 112, slightly enlarged). It is 
closely related to a cretaceous group, the Dysasteride. Finally, 
among crustacea, the sociable Arcturus Baffini (Fig. 113, about 
natural size) with its young clinging to its antenne is worthy of 
note as an arctic form. 
Many interesting mollusca were obtained, comprising a multi- 
tude of new species. Some dredgings in nine hundred and ninety- 
four fathoms off the Spanish coast revealed “a marvellous assem- 
blage of shells, mostly dead, but comprising certain species which 
we had always considered as exclusively northern, and others 
which Mr, Jeffreys recognized as Sicilian tertiary fossils, while 
nearly forty per cent of the entire number of species were unde- 
scribed, and some of them represented new genera.” On another 
occasion in seven hundred and eighteen fathoms off Spain the 
Verticordia acutilostata was taken. This shell ‘‘is fossil in the 
coralline crag, and the paces pliocene beds, and it now lives in 
the Japanese archipelago.’ 
In the final chapter the doctrine of the continuity of the chalk 
period with the present is discussed: in other words “that in the 
deeper parts of the Atlantic a deposit, differing possibly from 
time to time in composition but always of the same general char- 
acter, might have been accumulating continuously from the creta- 
ceous or even earlier periods to the present day.” 
The ‘t Depths of the Sea” is a work that every biologist should 
read, and for the general student of science it is the only general 
treatise on this subject. We hope so pleasant and thoroughly 
educated a narrator as Professor Thompson will be able to favor 
us with a similar work on the subject, at the close of his “ Chal- 
lenger” cruise. Certainly he will be in a position, if ordinary 
Success attends this important expedition, to give to the world, in 
Connection with American and German observations, results still 
_More comprehensive and conclusive than those flowing from the 
Cruises of the “ Lightning” and ‘‘ Porcupine.” 
CoLor-yartation IN BIRDS DEPENDENT UPON CLIMATIC INFLU- 
ENCES.*—The critic’s office is not seldom oa. shar and we have 
* On the rolati ‘n saal Tint Birds. as exhibited 
1 ee at 
in Melanism ikni l: By verran err Am, 
Jour, Say pgs ge vg 1872, p. 454; yd, 
