ELISHA MITCHELL SCIENTIFIC SOCIETY 64 
were set with their longest axes perpendicular to the adjoin- 
ing surface. The middle portion contained an irregular iron- 
stained cavity possibly due to the disappearance of some 
iron-bearing mineral. Several of the half embedded forms 
of Paleotrochis were cut in a hand specimen to discover its 
relations to the enclosing rock, and in each case it formed the 
interior portion of a spherulite. Most of them contained a 
dark green patch. The exposed conical surface of one was 
well striated and there was an irregular depression in the 
apex. ‘The form was composed chiefly of granular quartz 
with a yellowish brown to dark green, strongly pleochroic, 
biotite. Near the center is a small spherulite which is not 
only bordered by finer-grained quartz but is cut by a small 
vein of it, showing that the deposition of the quartz is subse- 
quent to the development of the spherulite. The embedded 
portion of Paleotrochis is bordered by spherulitic fibres which 
run approximately parallel to the slope of the conical surface, 
and it is evident that the casts of these fibers produce the ir- 
regular strie or grooves upon the surface of the supposed 
fossil. ‘The embedded portion terminated with an irregular- 
ly-pointed apex below. The whole form is fine-grained near 
the border and sends small veins into the adjoining spheru- 
litic shell. These veins are so small as not to be visible upon 
a polished surface of a hand specimen even with the aid of a 
pocket lens, but come out distinctly in the thin section. ‘The 
spherulitic shell by which Paleotrochis is enveloped is com- 
posed of fibers belonging to a number of centers or lines and 
yet combined they appear to form one nodule. The biconical 
form of Paleotrochis suggests that it originated as two spher- 
ulite sectors of which the apices were the centers from which 
the fibres radiated. ‘This would seem to be the simplest way 
to account for the most regular as well as many of the irreg- 
ular forms, but of the specimens examined I have not been 
able to find one that certainly originated in that way. 
A number of the fossil forms with a well-marked cup in the 
exposed apex turned out to be flat hemispherical or thin lenti- 
cular in section, and are composed wholly of spherulitic fibers. 
