72 
BULLETIN OF THE LABORATORIES 
extremity, where, after a shallow concave notch, the margin is convex. 
The remainder or the margin is strongly convex. From the above 
described ventral notch, a well defined, feebly convex, line passes 
dorsad to the opposite margin. That portion of the shell which lies 
cephalad of this line is usually curved laterad. From within the 
cephalad and caudad extremities of the valves numerous hairs pro- 
trude. 
In a dorsal view, the shell is sub-fusiform, being widest caudad 
of the middle. At their caudad extremity the valves are slightly 
divaricated, while at their cephalad extremity they are closely approx- 
imated. The shell is covered with fine reticulations and minute hairs. 
In addition to these, it is marked with conspicuous dark green bands. 
These bands are arranged as follows : One, parallel to and almost ad- 
jacent tothemesal border of the shell, extends from the caudo-ventrad 
angle of the shell dorso-cephalad almost to the cephalad extremity of 
the valve. There it divides. One portion continues in the same 
course to the cephalo-ventrad extremity of the valve. The other, turn- 
ing laterad, passes ventrad for a short distance and terminates in a 
sharp point. At the origin of this line there is a large, convex blotch, 
which extends ventrad a short distance. Near the centre of the figure 
several bands fuse in such a manner as to form a hollow, sub-square 
figure. From the cephalo-dorsad corner of the square a tongue passes 
ventro-caudad into the square. The length of this tongue and the 
angles it makes with the sides of the square vary slightly in different 
individuals. Usually it extends almost to the centre. From this same 
angle of the shell a band projects ectad. After passing cephalad a 
short distance, this band forms a convex curve and passes caudo-dors- 
ad almost to the margin of the shell. From the caudo-dorsad angle 
of the square a short band passes dorso-caudad and fuses with a 
broader band which passes caudad, approximately parallel to the dor- 
sal margin of the shell. From this same corner another band passes 
caudo ventrad almost to the caudad margin of the shell. This band 
is approximately parallel to the band just described. From the caudo- 
ventrad angle of the square a band passes caudo-ventrad almost to the 
caudo-ventrad extremity of the shell. In the caudad portion of its 
course this band curves dorsad, otherwise it is approximately parallel 
to the band last described. From the cephalo-ventrad angle of the 
square, a short band projects ventrad and then broadening, forms a 
boot-shape band. The short heel of this boot projects caudad and 
