458 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
In this species, the thick cuticle over the exoskeleton is often red 
brown and not only makes the zigzag plain but extending inward to 
line the cavity of the annulus, enables one readily to trace the clefts 
from the surface suture to the cavity of the trumpet. Thus in figure 
33 (pi. 47), which is the enlarged posterior part of a preparation like 
figure 21 (pi. 46), the three dark lines represent the first, second, and 
part of the third lines of the suture, and from these the closed clefts 
could be followed by focussing through the exoskeleton as far as the 
dotted line. This represents the inner end of the curved planes, or 
closed clefts, leading first from the median suture to the right and 
anteriorly to the last part of the trumpet cavity and next to the left 
and anteriorly to the semicircle of trumpet cavity shown on the left. 
These two planes crossing, there is a complex puckering and an exten¬ 
sion of the suture where the median and next suture lines meet. The 
cavity here represented empty was in reality full of sperm which 
extended forward far into the next arc as seen in figure 21 (pi. 46) and 
was then succeeded by wax that filled all the rest of the tube and the 
vestibule nearly to the last line. 
The above illustrations suggest that the trumpet is a long flat pocket 
open anteriorly and closed along the rest of its length; a pocket not 
straight but folded right and left and with its mouth drawn smaller 
than its bottom and thrown into sharp zigzag lines. 
Owing to the absence of such hard tuberosities as those of C. affinis 
and to the small amount of calcification, the annulus of C. virilis was 
readily cut into serial sections and the general structure found to be 
the same as in C. affinis. The exoskeleton that forms the walls of the 
trumpet is but an inward continuation of the exoskeleton of the rest 
of the annulus and the outer cuticle over the cravfish runs in at the 
V 
vestibule as well as along the entire suture to line the entire cavity of 
the trumpet which is thus morphologically but a pocket in the exo¬ 
skeleton. This exoskeleton pocket, however, lies upon a basis of 
epidermis and connective tissue that is like that in C. affinis and is 
the infolded living material that made the exoskeleton. 
At first C. virilis seemed to lack the peculiar part of the annulus 
called the ‘recess’ in C. affinis but closer study showed a small cavity 
comparable to the recess. In figures 21, 23 (pi. 46), and 33 (pi. 47) 
is seen a small curved sac posterior to the posterior end of the trumpet 
and somewhat to one side. This corresponds to the large heart- 
shaped recess of C. affinis seen in figures 27 (pi. 47) and 10 (pi. 43). 
