6o 'Review of <Recent Literature. 
considered the monticuliporoids as bryozoa, instead of corals, and in the 
course of his investigations divided and sub-divided the old genus Moti- 
iiculipora into a multitude, no less than eighteen different genera. At 
the same time a host of species were described, most of them from inter- 
nal characters, and they were illustrated by a profusion of drawings of 
the internal microscopic structure. Our opinion of this vast array of 
genera and species, and of microscopic work of tliis sort in general, will 
be given in detail later on in the present paper, but we cannot forbear 
saying that it is our belief that this work has resulted disastrously to the 
study of a confessedly difficult class of fossils; making it more difficult 
and confusing than ever before, and loading it with a mass of synonyms 
which of themselves are enough to deter one who should so desire, en- 
tering upon the study. The cavise of this we believe to be an erroneous 
method of study, and we ascribe the vast number of species and genera 
made to the almost exclusive attention given to microscopic characters." 
The authors discard all the genera that have been described by Nich- 
olson and Ulrich, and place known forms under two genera, Mo7iticuli- 
fora D'Orb, and Ccramopora Hall. Under the former they allow the 
sub-genera Dcknyia Ed. and H., Constellaria Dana, and FistiiUpora Mc- 
Coy. These distinctions are based on external characters of form and 
habit. They object to the use of internal characters in determining 
species and genera, "because they entail an immense amount of work 
which in the end seenls to amount to very little." They also consider 
the internal characters more variable and unsatisfactory than the exter- 
nal. They allow, however, that "there is, in fact, no criterion by which 
to judge fossil species, except individual opinion." We should be sorry 
to see any minute research with the aid of the microscope, into the in- 
ternal structure of fossils, discountenanced and retarded because of the 
difficulty of the work. There may be, and doubtless have been, more 
species created on paper than actually exist in nature. As to the value 
of the differences that any investigator may discover, he is likely to 
over-estimate it. But it is very doubtful whether such differences would 
be searched out and recorded if the investigator did not himself feel sat- 
isfied of their importance, be they external or internal. His record of 
them, while it multiplies species, is the most effective record, and is, of 
itself, no detriment to the progress of science — butrather an aid. There 
is, as yet, no accepted limit nor limitation to an organic species, and 
there is no restriction to the use of individual opinion. Ultimately per- 
haps some biological principles may be established by which species 
may be defined. When such is the case they may be applied to the 
elimination of some of the specific names, or to the recognition of much 
finer and more numerous distinctions. 
A spiral bix'dlvc s/icll from the ]\'avciiy group of Pcimsyli'diiid. By 
CiiARLF.-s E. Beecher. (From the thirty-ninth annual reportof the New- 
York State Museum.) Mr. Beecher describes and figures a new genus 
and species, Spirodoiiius i/zsiot/is, of lioring molluscs, from what he con- 
