AGASSIZ. NATURAL HISTORY OF THE UNITED STATES. 405 
clidie have not the same organic complication as the Diphyidse, while 
the Prayidse have.” With regard to the doubtful species of Sipho- 
nophora, “ described by Quoy and Gaimard in the Zoology of the 
Astrolabe, most of which are figured from imperfect specimens,” 
Professor Agassiz has here 44 attempted to classify them, according 
to the method so successfully applied in the study of fossil remains, 
comparing the parts preserved and illustrated by the Prench zoolo¬ 
gists, with corresponding parts of the European species, now fully 
known by the extensive researches of Milne-Edwards, Kolliker, 
Leuckart, Vogt, Gegenbaur, and Huxley.” Such a method of treat¬ 
ment has, at least, the merit of ingenuity, and cannot fail to be fol¬ 
lowed in practice by those who have leisure and inclination for so 
doing. But the conjectural results thus obtained, however desirable 
it may be to embody them in supplemental lists, ought by no means 
to find a place in the more permanent nomenclature of scientific 
zoology. There is, also, a distinction between the study of figures 
and of objects themselves. The imperfect knowledge which must con¬ 
tent us in the case of fossil remains, seems scarcely worth striving 
for, when we pass to existing organisms of which uninjured speci¬ 
mens will, doubtless, in due course, be met with, and examined with 
every aid to complete investigation. 
We have read with some surprise the statement of Professor 
Agassiz that, in characterising the Siphonophora he has “ purposely 
avoided the special nomenclature devised by the German naturalists 
to describe the Siphonophorse, and reproduced in an Hellenic garb by 
Huxley, in order the more directly to show the close affinity of these 
animals with the Hydroids. It is a fact constantly recurring in our 
science, that special names are required to designate the parts of 
animals, the homologies of which are not fully ascertained ; but as 
soon as their structural identity ceases to be doubtful, it seems to 
me best to discard such technicalities, and I believe the time has 
come when the Siphonophorse may be described in the same words 
as other Acalephs.” In reply to this we feel ourselves compelled to 
say a few words. The writers to which Professor Agassiz here refers, 
particularly our English colleague, do in fact describe the Siphonophora 
in the very same words as other animals belonging to the same class, 
and insist strongly on the homologies existing between them. The 
44 General Introduction” prefixed to the Bay Society’s Monograph of 
the Oceanic Hydrozoa has always appeared to us written with a view to 
establish and demonstrate the very position which Professor Agassiz 
would now claim for himself. As to the technicality of the nomen¬ 
clature (or, more correctly, the terminology) which he condemns, w T e 
do not see in what respect such words as 4 polypite ’ 4 coenosarc ’ and 
4 gonophore’ are a whit more abstruse or deterrent than some of his 
own terms, for example,— 4 spherosome,’ 4 abactinal ’ and ‘ hydro- 
medusarium !’ 
Part IV. concludes with a few lines on the Geographical Dis¬ 
tribution of the Hydroidce , in which the Author expresses his opinion 
N. H. R.—1863. 2 L 
