146 
BE VIEWS. 
passage other ingredients of different character from those which they originally possessed, 
or larger proportions of one or other of their original ingredients. In those places or at 
those times when violent accessions of heat approached most nearly to the surface, 
trachytes and felstones might be poured out, while at other periods of less intensity no 
molten rock could reach the surface unless it were composed of more easily fusible mine¬ 
rals. These more readily fusible substances might be conceived either to have separated 
in liquid strings and veins from the consolidating rocks below, or to have been acquired 
by the upper portion of the mass from the rocks it met with in its passage towards the 
surface, the substances thus added having acted as an additional flux to matter which 
would otherwise have solidified before it could have been poured out.” 
The second and third parts of this hook do not appear to ns to he so 
well adapted to the student’s wants as the first part on Geognosy. 
They treat of Palaeontology and Geology proper; and discuss the subject 
of fossils biologically and historically. The student will complain of the 
absence of all illustrations; and we think that Mr. Jukes would have 
better consulted his readers’ wants if he had confined his attention to 
characteristic fossils, and given a general and masterly account of the 
history of organic life on the globe, and of its distribution over its sur¬ 
face. He has allowed himself, as we think, to be carried away too 
much with the details of his subject, and has thus given the appear¬ 
ance of a mere catalogue of names to the most interesting branch of 
Geology. The learner, using Mr. Jukes’s book, must find out for him¬ 
self that this portion of it is intended to be referred to, and not read; 
and should he, unfortunately, like ourselves, spend an evening or two 
in its serious perusal, he will, most likely, suffer from a palaeontolo¬ 
gical nightmare, in which Pictet, Jukes, and Morris, will have a large 
share; or should he lie awake, he must experience sensations similar to 
those of a student who has rashly attempted to read the catalogue of the 
ships in the second book of Homer. 
These two parts of the book should check each other, like book¬ 
keeping by double entry; as the fossils are entered in the first part 
zoologically, and in the second part, chronologically. This circumstance 
would render such lists of great value to the student for reference; but 
their entire value depends on the accuracy with which this is accom¬ 
plished. 
The following is Mr. Jukes’s preface to the work of tabulating the 
fossils zoologically:— 
“ I have determined to lay before the student in this chapter a classified catalogue of 
fossil animals and plants, in order, first, to give him an idea of the richness and extent 
of the domain of palaeontology, and, secondly, to furnish him with a reference as to the 
nature of any particular fossil he may find mentioned in this or other works, and also to 
place before him the main facts of the distribution of fossils in time. This latter subject 
will anticipate somewhat that which properly belongs to the third part of this work, but 
its utility will countervail, I hope, any breach of logical sequence. 
“ I have taken Pictet’s Palaeontology as my guide with respect to fossil animals, 
having merely re-arranged or transposed some of the matter to make it suit the classifi¬ 
cation previously given a little more closely. 
“ I have not, however, attempted to do this throughout, and the student will take any 
variation in the two classifications as a hint that systems, however necessary, are, after 
all, more or less arbitrary and imperfect, representing often rather the limited powers of 
