lOO 
BULLETIN OF THE LABORATORIES 
lution ; aperture not distinctly preserved, but apparently the aperture 
was dorsally sinuate, the sinuation being simple and broadly V-shaped : 
this, however, can not be conclusively determined. Umbilicus quite 
large, and deeply defined. Dorsally the curvature of the shell 
toward each side is even and moderate, laterally the curvature is very 
sudden, the curvature of the sides into the umbilicus equaling or even 
exceeding the dorsal curvature of the shell ; by this means the umbili- 
cus is deepened and the sides of the shell appear raised, 3,lmost cari- 
nated towards the aperture. 
Surface marked by fine longitudinal striae, of which thirteen may 
be counted on each side of the carina as far as the beginning of the 
umbilicus, these are increased by intercalations with the age of the 
shell. Transverse striae in the direction of the lines of growth, the 
striae on opposite sides of the carina having an angle to each other 
equal to that which the sides of the sinus of the aperture seem to have. 
A third, less distinct system of striae, originating at the carina, seems 
to make about the same angle with the longitudinal striae as the trans- 
verse striae just described. As a result of all these striations, the sur- 
face of the shell is divided up into many minute, many-sided polygons 
which give the shell a beautiful appearance. This is enhanced by a 
low, distinct carina, slightly raised at the sides and thus becoming 
grooved. Along the carina only afew, indistinct, longitudinal striae 
are here and there visible, there are however many fine transverse 
striae, bending backward into the groove of the carina. 
Greatest diameter (extending through the aperture), ii mm.; di- 
ameter transverse to this, 9 mm. Diameter of the last volution at its 
beginning, 2.5 mm.; at the aperture, the diameter passingThrough the 
dorsum is 5 mm.; the one transverse to this, 9 mm. The width of 
the carina, .4 to .5 mm. 
Locality and position. Stolz’s Quarry, Clinton Group. 
Crustacea. 
I. 
Acidaspis , 
II. 
Bathyurus, , 
III. 
Illaenus Daytonensis, 
. Hall and Whitfield. 
IV. 
— Madisonian us. 
Whitfield. 
V. 
— ambiguus. 
n. sp. 
VI. 
Calymene , . 
. 
