BY .IAS. 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 j^roboscis gut lumen into the mouth 

 cavity, at first narrow, ])ecomes 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. 1-3). 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 jDasses into 

 the body proper. By the union of the dorsal edges of the " end 

 plate " there is sometimes formed a blind canal continuing foi- a 

 short distance into the bod}^ 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 

 V-shaped structure with widely divaricated legs. It is separated 

 from the end plate by a thin Imnd 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, kps.). The " body " 

 has at first a semilunar outline, with the flat side immediately 



