REVIEWS 221 
degradation. In the degradation of such a plane the material is not 
taken up once for all and carried out to the sea (except of course that 
held in suspension), but is shifted little by little through cutting here 
and filling there, until, piece by piece and shift by shift through almost 
endless repetitions, the material is at length transferred to the sea. 
The newly formed portions of the equated plane would be liable to 
suffer this process over their whole surface during the stage of equilib- 
rium and the early stages of degradation. It would be only when 
the degradation of the portions down stream had increased the gradient 
to such an extent as to lead to a contraction of the channel and the 
abandonment of a portion of the flood plane, that reworking of the 
surface parts would cease. 
If, therefore, we assume the style of fluvio-glacial deposition postu- 
lated by Professor Wright, we find definite reasons for regarding the 
upper part of the Brilliant deposit as postglacial in origin, and find 
moreover special conditions that may have subjected it to reworking 
during the early stages of degradation that followed its construction. 
If, on the other hand, we assume that the glacio-fluvial deposits took 
the form of a common aggradation plane at the close of glacial action, 
the presumption is that the Brilliant terrace was carved out much later. 
It is just possible that the Brilliant deposits happened to be at the 
pivotal point between degradation and filling, and so were original — 
and the review admitted that they might be—but the more the case is 
studied the less probable this seems. A Core 
North American Fossil Crinoidea Camerata. By CHARLES WACHS- 
MUTH and FRANK SPRINGER. (Memoirs Museum of Com- 
parative Zodlogy.) Two parts, 800 pages, and atlas of 83 
plates. Cambridge, 1895. 
During the decade just passed our knowledge of ancient organisms 
has been enormously expanded, not so much through the old grooves 
of endless multiplication of species, as along lines in which the most 
recent conceptions of morphological inquiry are taken into considera- 
tion; or along lines having a direct bearing upon the interpretation of 
geological phenomena. Hence the differentiation of modern paleon- 
tology has been chiefly in two directions, and these departments are 
becoming so widely divergent that they willere long, if some energetic 
steps are not taken to prevent it, cease to be of mutual aid. The 
