406 The American Naturalist. [April, 
The case is fitted for 3 inch by 1 inch glass slips of any thickness, 
and has a capacity of six to twelve dozen. It has four compartments 
for the cover-glasses of the sizes 4 inch, $ inch, ł inch, $ inch, or 12mm, 
to 24mm., either circles or squares or oblongs of the above widths, and 
any lengths up to 2} inches. The screw stops regulate the depth of 
the slots for either No. 1, 2 or 3 thickness of cover-glasses. 
Plate VII is a vertical section from front to back, showing the plan 
of the case. The section of the lower half is made in the median plane, 
that of the upper half in the plane of a screw stop. Through the 
base (b ) projects the stop (s ) into a narrow groove in the mounting 
table ( mt ) which slides in and out between the base and the floor (f) 
of the stock compartments (sc’). The service compartment (sc) is 
deepened by a shallow cavity cut into the upper surface of the mount- 
ing table, and in the bottom of this cavity is fitted a sheet of celluloid 
bearing a series of concentric lines. The slips ( ss ) are stacked in the 
service compartment, the lowest slip filling the shallow cavity in the 
mounting table as shown at (ss’). A warning slip of paper ( ws ) is 
folded around the front edge of the top slip. The loose partitions ( p ) 
running in grooves in the sides of the case can be removed after slid- 
ing back the cover (c). In the base (f’) of the cover-glass case is the 
groove (1 ) for the roller (r ) which is made of brass and covered with 
chamois. To the front of the base is hinged the brass dust-excluder 
(de) whose lining of silk plush protects the grooved table (t) and the 
slot (sl) from dust. The dust-excluder also prevents the delivery of 
a cover glass by the roller except when the slot is opened. Into the 
slot projects the point of the serew-stop (st ) which is so adjusted as to 
permit the passage into the slot and out upon the grooved table of only 
one cover-glass at a time. Above the roller are stacked the cover- 
glasses (cg). Near the top of the stack is placed the warning disk 
(w) and upon the top cover-glass rests the loosely-fitting follower 
(cf) which prevents displacement and breaking of the covers, if the 
case is accidentally overturned. The adjustable partition ( ap) may 
be moved backward or forward to fit any length of cover-glass from 
} inch to 2? inches. The cover (c) is so constructed as to exclude 
ust. 
Plate VIII is a front view of a form of the case as made for one size 
cover-glass, either circles or squares, and of either ŝin., łin., or žin. 
diameter. The open dust excluder is hinged above the slot at the sides 
of the case. The engraving does not show the groove in the table in 
front of the slot. A slip is shown in position in the mounting table. 
One of the lateral grooves in the mounting table is not represented. 
