jukes’S MANUAL OF GEOLOGY. 
147 
the human mind than the infinite variety and superabundance of nature. I have also 
ventured so far to disturb Pictet’s arrangement as to place the extinct genera of each 
family or order by themselves, preferring to mark their geological history more strongly 
than their zoological relations. 
“For the plants, I have only given an abstract of those mentioned in Bronn’s Index 
Pakeontologicus, with very few additions.” 
Mr. Jukes defines a fossil as “ the body, or any portion of the body, 
of an animal or plant buried in the earth by natural causes, or any re¬ 
cognisable impression or trace of such a body, or part of a body:” a 
definition precisely similar to that laid down several years since by Sir 
Charles Lyell in his “ Elementary Manual of Geology.” After a few re¬ 
marks on the nature of “ petrifaction,” Mr. Jukes, as a necessary intro¬ 
duction to the right comprehension of the facts of Palaeontology, presents 
his readers with classificatory tables of the two great kingdoms of the 
organic world. His classification of the animal kingdom (with the ex¬ 
ception of that of the Mammalia, in which he follows the arrangement 
of Professor Owen) has been supplied to him, we are informed, by his 
friend, Professor Huxley. But though the system here given corresponds 
with that adopted by the eminent naturalist whose name we have just 
mentioned, in some particulars—such, for example, as the recognition 
of the Protozoa and Coelenterata as distinct sub-kingdoms, and in regard¬ 
ing the Echinodermata as a class of the Annulosa-—yet in other respects 
it is widely different; and we are of opinion that some error must have 
been committed by Mr. Jukes in interpreting the views of his distin¬ 
guished colleague. Thus we are told that the Hydrozoa are divided 
into two orders only—Lucernaroida and Hydroida; whereas we have 
always understood that Professor Huxley considered this class as con¬ 
sisting of several orders, certainly of not less than five. Again, on the 
same authority, the Bugosa are separated from the Zoantharia of Milne- 
Edwards, and regarded as a distinct order in themselves; whereas, in 
the published Lectures of Professor Huxley they are plainly stated to con¬ 
stitute a subdivision of the Alcyonaria. The true position of this in¬ 
teresting group of corals is certainly well worthy of consideration, and 
we would fain digress awhile from our subject to dwell on a topic so 
important, more especially since Professor Agassiz, in a letter to Dana, 
the distinguished American zoophytologist, has recently given it as his 
opinion that not only they, but likewise all the Tabulata, including the 
Milleporidse, Eavositidse, Seriatoporidse, and Thecidse, should be re¬ 
moved from the class Actinozoa, and transferred to the Hydroid division 
of the Coelenterata sub-kingdom (“Silliman’s Journal,” July, 1858). 
To return, however, to Mr. Jukes’s Manual. After briefly noticing 
the general laws of distribution, he commences the subject of Palaeon¬ 
tology proper by presenting us with along “ Abstract ofEossil Genera,” 
occupying somewhat more than fifty pages. In this “ Abstract” Mr. 
Jukes very properly arranges the different genera enumerated under 
their respective families, orders, and classes; whilst after the name of 
each genus he has appended initial letters indicative of the geological 
formation to which it belongs,—such as I). for Devonian, S. for Silurian, 
