BY JAS. P. HILL. 
13 
which the gland cells are situated, radiate outwards from the 
lumen. They have elongated, rod-like nuclei situated at about 
their middle region, and on the dorsal side their outer ends come 
into connection with processes from an irregular layer with 
rounded nuclei situated immediately below the limiting membrane 
of the notochord. On the ventral side the passing over of these 
distinct epithelial cells into the chorda-like tissue can be distinctly 
recognised (figs. 9 and 12, dv.). 
In correspondence with the widely diverging legs of the proboscis 
skeleton the opening of the proboscis gut lumen into the mouth 
cavity, at first narrow, becomes eventually a very wide transverse 
opening, in the anterior part of the mouth cavity. I have also 
encountered in the proboscis gut the yellow granules which 
Spengel regards as excretions. 
Proboscis Skeleton; it consists, as in the described 
species, of a main body, a keel-like ventral portion, and two 
posterior diverging legs (fig. 13). The anterior portion of the 
body is formed by the funnel-like " end plate " which invests the 
ventro-lateral regions of the ventral blind sac of the notochord. 
The lateral edges of this plate extend somewhat in front of the 
ventral, so that they appear first in sections as two thin plates 
investing the lateral faces of the blind sac (fig. 9, eps.). The 
anterior "end plate" gradually narrows posteriorly, its dorsal 
edges unite with each other in the median line, and it passes into 
the body proper. By the union of the dorsal edges of the " end 
plate " there is sometimes formed a blind canal continuing for a 
short distance into the body proper, and occupied by a prolonga- 
tion of the " chorda-like tissue " of the hind wall of the ventral 
blind sac. The " keel " first appears at a short distance behind 
the anterior edge of the " end plate " in the form of a small 
Y-shaped structure with widely divaricated legs. It is separated 
from the end plate by a thin band of " chondroid tissue." Then 
gradually the ventral apex of the keel thickens and gives rise to 
a distinct ventrally projecting tooth-like portion, the keel now 
having in section the form of a Y (fig. 10, hps.). The "body" 
has at first a semilunar outline, with the flat side immediately 
