XXXIV.— CONTRIBUTIONS TO THE NATURAL HlSTORA OF THE 
United States of North America. By Louis Agassiz. Vol. 
IV. Boston, 1862. 
The fourtli volume of Professor Agassiz’ £ Contributions ? has now, 
for some months, been on our table ; and we proceed, according to 
promise, to lay some account of its contents before our readers. 
It will be remembered that the preceding volume* of the same work 
contained tbe two first parts of the Author’s £ Second Monograph,’ 
which treats of the Acalephs. These parts were entitled 6 Acalephs 
in General,’ and £ Ctenophore.’ In the present volume this mono¬ 
graph is continued and, apparently, brought to a conclusion, though 
Professor Agassiz speaks, more than once, of resuming the discussion 
of portions of its subject-matter on a future occasion. 
The bulk of the volume is engrossed by Parts III. and IV., on 
the £ Discofhor^ ’ and £ Hadroide,’ these, with the CTENOPiioRiE, 
forming the three orders into which, according to Professor Agassiz, 
the class Acalephse should be divided. Nearly 400 pages of text 
and 17 plates are thus occupied; to which should be added 23 (out 
of the 26) plates in Vol. III. which refer solely to the DiscophW.cs 
and Hydroidce. Lastly, there is here a fifth, and much smaller 
Part, on the £ Homologies of the Badiata.’ 
We have seen that the class of Acalephs, as thus extended and 
revised, includes the Acalephce of Eschscholtz, together with the 
Hydroida and Lucernariadce of Johnston. Both Johnston and 
Milne Edwards have associated the last mentioned family with the 
Actinoid Polypes. Except as to this particular (and another, to be 
presently stated), the Acalephw of Milne Edwards and Agassiz, in 
their entirety, correspond, though there is not quite the same accord¬ 
ance between these two eminent naturalists, both, it must be 
remembered, original investigators of the most varied typical 
forms belonging to the group, as to what ought to be considered its 
primary divisions. This will appear from the accompanying table. 
ACALEPHS. ACALEPIIES. 
Agassiz. Milne Edwards. 
Order 1. Hydroidae . . . J Classe 1. Hydraires. 
,, 2. Discophorse t ( „ 2. Siphonophores. 
„ 3. Ctenophorae i . . „ 3. Medusaires. 
The order Hydroidce of Agassiz is even more extensive than the 
above comparison would seem to imply, for, besides the Hydroida 
of Johnston and Siphonophorce of Eschscholtz, it contains most of the 
Discophorce referred by the latter naturalist to his second section, 
Cryptocarpce , in addition to the Tabulate, Tubulose and Bugose 
Corals, placed by all other systematists among the Polypi. 
* Noticed in Natural History Review, October, 1861. 
