146 Scientific Intelligence. 
necessary. The monograph contains an historical account of the 
principal results obtained by previous writers on the subject, show- 
ing the successive steps which oe brought about the present 
mous  Biydees oa. The main points of MeCredy? 8 imma were 
taken for Professor Agassiz’s lectures, though this was not suffi- 
ciently distinctly stated by McCrady in his paper on the Acalephs 
of Charleston harbor. 
A very systematic terminology is ee which, even when 
we do not agree with the views o man, cannot fail to pee 
accuracy and prevent the ambiguity so common in our scrip- 
bai of Hydroids, as the new terms a can be readily re- 
— red and are of a nL ris 
general presentation of the subject is pn ed, 
pass current among the most competent of the investigators of 
the subject, the principal difference poco me ng in adopting as 
zodids, and not as individuals, the representatives of the different 
phases of development, the zovids as a whole forming the indi- 
vi 
of ‘Ses animal ing dom. 
We have an interesting chapter upon the geographical distribu- 
tion of yaoi 8, which, for the — materials as yet collected, 
which to base reliable conclusions. The limitation ot spec 
their definite areas is very remarkable, though it may a a 
more to negative than to positive evidence. As far as the North 
Atlantic is concerned, which is better known than any other 
great realm, we are not yet in condition to distixignich its prov- 
inces accurately. e question of the difference of many of our 
a “i 
means so settled as has been taken for granted. In fact, prese sent 
evidence rather tends to show a wide range in the distribution of 
