Geology and Mineralogy. — 157 
by the column, so as to be difficult, and in many cases impossi- 
ble, to distinguish. 
By cutting, grinding and breaking many specimens, Wachs- 
muth and Springer have discovered that there is a regular alter- 
nation in the arrangement of the successive parts below the 
radials. The basals are interradial in position and all under- 
basals are radial. The exterior angles of the column, if it be 
angular, alternate with the ring of plates next above it; and if 
the central canal in the column be. angular, its angles alternate 
with those of the column. So, if in relation to the calyx plates 
above, the exterior angles of the column are found to be radial in 
position, the ring of plates next above, being alternately ar- 
ranged, will be basals, and consequently underbasals are wanting. 
If, on the contrary, those angles are interradial, the next plates 
in succession above will be radial, and hence underbasals. If 
the column be round, and the axial canal angular, the angles of 
the latter may be consulted; if radial, underbasals are present ; 
if interradial, they are absent. Similar results are given by the 
cyrri when they exist; and by the segments of the column, when 
divided longitudinally, as sometimes happens. 
It thus becomes possible to distinguish between underbasals 
and the top segment of the column, which has hitherto been 
often attended with difficulty. The authors assert that this rule 
is applicable without an exception to the paleozoic crinoids. 
An appendix to the work contains two articles. In the first 
the authors place the genus Stephanocrinus among the Palzo- 
crinoidea, assigning it to the Larviformia. Roemer and J. 
Muller had previously referred this genus to the Cystidea; and 
later, Etheridge and Carpenter referred it to the Blastoidea. The 
latter authors seem to have regarded the evidence adduced by 
Wachsmuth and Springer as conclusive, for in their lately-pub- 
lished catalogue of the Blastoidea they omit Stephanocrinus. 
In the second article they apply the rules which they have 
found to govern the structure of dicyclic and monocyclic Palzo- 
crinoidea, to the later crinoids; and they come to the conclusion 
that the Apiocrinoide and Comatule are constructed upon the 
plan of dicyclic crinoids; and that in their larval state they 
probably had rudimentary underbasals. If hereafter those plates 
should be discovered their existence will have been predicted 
upon paleontological evidence, and as the result of comparative 
studies. 
The second section of Part IIL completes the work as the 
authors originally planned it; but they have begun the prepara- 
tion of a monograph of the Paleozoic Crinoids of North America, 
which they intend to make the most extensive illustrated work 
on Crinoids ever produced. Paleontologists will await the results 
of their newly self-imposed task with great interest. C..A. W. 
4, A card to American Geologists.—A meeting of the Ameri- 
can Committee of the International Congress of Geologists, will 
be held in Albany from April 6 to April 9, 1887. 
