xliii 
(a number of copies of which have been in the publisher's hands 
for the last two months). The work is to be completed in four 
parts, with forty plates. 
Dr. Barrande still continues his " Researches on the Silurian 
Fossils of the Centre of Bohemia," and has discovered that, 
whilst in the Cambrian formation not more than twenty-eight 
animals have been discovered, in the Primordial Silurian system 
not fewer than three hundred and sixty-six have been found, of 
which two hundred and fifty-two are species of Trilobites, ten of 
Ostracoda, and only two of other Crustacea, distributed in that 
system of rocks, as follows : — 
Europe. 
North America. 
i 
S 
a 
1 
1 
^ 
1 
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1 
Classes. 
<3 
a 
i 
1 
i 
% 
.2 
"2 
pq 
o 

1 
Vn 
a 
.a 
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g 
•a 
^ 
^ 
ii 
2 
Pi 
^ 
n 
m' 
02 
M 
9 
9 
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18 
!zi 
6 
1 
37 
8 
1 
28 
Trilobites . . 
27 
9 
77 
61 
2 
Ostracoda . . 
- 
1 
5 
4 
- 
- 
- 
- 
- 
- 
- 
- 
2 
Other Crustacea 
- 
- 
- 
1 
- 
- 
- 
- 
- 
1 
- 
- 
An important memoir, by G. 0. Sars, published in the Trans- 
actions of the Royal Swedish Academj^ (Kongl. Svenska Vetensk. 
Akad. Handl. vol. ix.), has only recently reached me. It is 
devoted to the species of the very interesting Crustaceous group, 
Cumacese, allied to the Mysid?e, a group which has attracted the 
attention of some of the most learned of recent Crustaceologists, 
who have greatly differed in their opinions of the homologies of 
the parts of the mouth and anterior pairs of legs ; thus the organs 
which Kroyer and Spence Bate regard as the first, second and 
third pairs of true legs, were considered by Goodsir as the second, 
third and fourth pairs of legs, by Van Beneden as the second and 
third pairs of gnathopods and first pair of legs, and by Anton 
Dohrn as the second pair of gnathopods and the first and second 
pairs of legs. By Sars, the three short terminal pairs of thoracic 
