THE PALEONTOLOGIC RECORD 143 
of many structures can not be elucidated, even by the embryology and 
comparative anatomy of the recent forms, but only by paleontology. 
Such a structure is, for instance, the mystifying stem of the crinoids 
which, by a study of the primitive ancestors of the crinoids among the 
eystids, is readily recognized as a dorsal evagination of the body. 
Likewise, to cite another example, the siphuncle of the recent Nautilus, 
which is obscure as a wholly rudimentary organ, is in such primitive 
Paleozoic cephalopods as Nanno and Piloceras, still seen in its original 
form and thereby recognized in its nature. 
Since that which has already been accomplished in fossil anatomy 
is proof that there are still larger fields to be ploughed and harvested, 
it is proper to inquire into the best methods of this work before us. 
We first need more extensive and more intensive or more detailed 
purely descriptive anatomical researches of the invertebrate fossils. 
There are many species that, when investigated in their smallest detail, 
are bound to give important results. I may cite here, as examples of 
such accomplishments, Hudson’s minute study of the strange Blas- 
toidocrinus of our Chazy rocks with its 90,000 ossicles, or that of the 
Eurypterus fischeri by Holm. Of this archaic fossil marine arachnoid, 
a relative of the scorpion and of the king crab, it can be fairly said that, 
as far as its chitinous integument is concerned, it is as well known as 
any recent species. We know, through Holm, its gills, its complex 
genital appendages of both sexes, and even its fine hairs and bristles. 
Dr. Clarke and myself have lately continued these investigations in 
the American eurypterids, and there observed the structure of the com- 
pound eyes, the pore system of the segments, the genital apertures, the 
mode of moulting, the arrangement of some of the principal muscles 
and other anatomical facts of interest. 
It can be said that this field of detailed descriptive anatomy has 
been merely touched thus far, as far as our fossil invertebrates are con- 
cerned, and altogether too much neglected. This is not only true as to 
the gross anatomy, but still more so as to the microscopic structure. 
It must be conceded that owing to the secondary changes in the rocks, 
this latter line of investigation meets with great obstacles not fully ap- 
preciated by the zoologist, and that it is only in its infantile stage in 
some classes. But the results obtained by the microscopic research of 
the Paleozoic bryozoans in this country may be considered as a striking 
example of what persistency and enthusiasm may still accomplish. In 
microscopic anatomy of the fossils the training of a geologist is as 
much required as that of a zoologist and the history of these investi- 
gations shows that a zoologist without geologic training may be badly 
misled by the deceptive states of preservation of the fossils. 
The main object of anatomical research is to result in comparative 
anatomy and to determine what parts are fundamental or primary and 
