64 KANSAS ACADEMY OF SCIENCE. 
FUSULINA CYLINDRICA SHELL STRUCTURE. 
BY ALVA J. SMITH, EMPORIA. 
Read before the Academy October 28, 1897. 
The living Fusulina cylindrica was a member of the animal sub-kingdom 
Protozoa, class Rhizopoda, order Foraminifera, family Nummulitidae. 
The shape of the shell of the young is a spheroid, but changes during the 
growth of the animal to an ovaloid, which resembles a grain of wheat in both 
form andsize. Theshell is composed of longitudinal chambers arranged spirally 
around a central spherical chamber, making about ten complete whorls in the 
adult shell. 
The average length of the Fusulina is about 6 mm. and the thickness 2.5 
mm. The spheroidal nucleus or central chamber is about 1-10 mm. in diameter 
and is provided with many circular openings, through which the animal pro- 
trudes its thread-like pseudopodia, and is connected by a small open’entrance to 
the second chamber. 
The second chamber is about 3-100 mm. in width, while its length embraces 
slightly over one-half of the nucleal chamber. Each succeeding chamber 
extends a little beyond its predecessor. This lapping of the chambers at the 
ends causes the increase in the longitudinal dimensions of the shell as it grows 
by the addition of chamber after chamber. 
The size of the chambers and the thickness and strength of their walls in- 
crease from the center out. An open passage bearing a resemblance to the 
siphuncle in cephalopods lies as a trough along the ventral side of the chambers 
and cuts away the lower half of the septa where it passes through them. 
The name ‘‘involute sinus’’ has been proposed by Professor Williston for this 
’ trough-like passage. The width of the openings in the septa increases from about 
oJ; mm. at the nucleus tol mm. in the outer whorls. The septa are also punctured 
by many minute circular openings (foramina) which were once occupied by the 
pseudopodia of the animal, and later served as ways for the protoplasm of the ani- 
mal to communicate from chamber to chamber. 
The outer walls of the chambers possess very few if any foramina or other 
openings. They are slightly more convex than the general curve of the whorl, 
and extend in graceful double curves from the girdle to either end, giving a 
corrugated appearance to the outer surface of the shell. The living Fusulina 
was evidently one composite body, occupying all the chambers of the entire shell 
at the same time, with a common vitality; a continual circulation of protoplasm 
taking place from chamber to chamber through the minute foramina and the 
siphuncle-like openings in the septa. 
The first chamber occupied by the young Fusulina is nearly spherical. A 
spherical first chamber is found in a great number of Foraminifera whose later 
forms bear no resemblance to a sphere, the form of the succeeding chambers and 
the final shape of the adult shell depending upon the order in which the multi- 
plication of chambers takes place and their manner of attachment to the parent 
mass. 
In the Fusulina the animal occupied the central spherical shell for a time; 
then a portion of its ameboid contents spread out through an opening in the 
shell, forming a belt about ;3,;mm. wide on the outside, its length embracing 
slightly over one-half the perimeter of the shell. 
This strip of living matter soon secreted a calcareous covering, which is the 
second chamber of the shell. The third chamber is formed by a similar process 
