Fig. 
EXPLANATION OF THE PLATES. 
PLATE 1. 
Proneomenia siuiteri. Drawn from the spirit-speeimen. 
0. the mouth. 
The same. Smaller sized specimen. In both these figures the ventral 
groove is partly turned towards the spectator. 
The anterior extremity of the body, viewed from below. 
o. the mouth, separated by a bridge of the integument from 
f. the slitlike opening of the anterior foot-gland. This slit is 
immediately continued into the ventral furrow. 
The posterior extremity of the body viewed from below. 
a. the exterior opening of the anal cavity, continuous with the 
venträl furrow. 
Two spieulae of the integument from the anterior body-region. Drawn 
with the camera. Magnified. 
The exterior, surface of the integument seen from above with weak 
powers. The intercerossing of the spicules takes place in two pre- 
dominating direetions, each ot which makes an angle of about 40° 
with the body-axis. 
A growing spieule from the anterior body-region. 
s. the base of the spicule inclosed in 
b. the cellular bag in which the secretion of carbonate of lime 
goes on and which remains in continuous connection with 
the cellular matrix of the integument by a partly fibrous 
pedicle. 
u. nuclei in the walls of this bag and in the pedicle. 
