474 
PROFESSOR J. STEPHENSON AND DR BAINI PRASHAD ON 
the triangle, which is towards the oesophageal lumen, is broad, and the angles of 
neighbouring triangles may almost meet ; so that, under the low power, the 
straight and almost, continuous bases of the triangles simulate, all taken together, 
a continuous basement membrane of the oesophageal epithelium. 
Towards the hinder end of the gland, where the oesophageal epithelium has 
again become regularly ridged, the loose reticulum beneath it disappears, so 
that the whole epithelial layer becomes denser in its texture ; the intervals between 
the neighbouring angles of the triangular dilatations of successive sinuses are 
necks through which the epithelium of the oesophageal lumen is continuous 
with the epithelium of the tunnels. The whole extends to the hinder end of 
segment xiv. 
There are no definite openings of the tunnels into the oesophageal lumen ; there 
are, perhaps, very occasionally in segments xi and xii indications of the possibility 
of a communication ; but these passages resemble, and may actually be, accidental 
breaks in the continuity of the oesophageal epithelium, and appear to us to be of 
no morphological importance whatever. They quite obviously do not occur in con- 
nection with all or the majority of the tunnels, and the tunnels are continued back 
beyond these breaks. 
The number of lamellae, at one place 62 or 63, become further back 68—72. 
Helodrilus parvus. 
The anterior part of the oesophageal pouches, in segment x, is almost smooth. 
Further back, the epithelium of the oesophageal lumen bears very marked rodlets, 
which come out with extreme distinctness in a chrome-hsematoxylin stained pre- 
paration. These persist to the end of segment xiv ; here the canal widens, and the 
layer of rodlets is replaced by a homogeneous, lightly staining, cuticle-like layer. 
The texture of the deeper portion of the oesophageal epithelium is even looser 
than in the foregoing species ; there are large clear spaces, unoccupied even by 
trabeculae or strands. 
In segment xi there are 27 tunnels, and 30-32 further back ; in another specimen 
38-44 were counted. The tunnels were not, in any of our specimens, much elongated 
in a direction radial to the axis of the oesophagus — they were never more than 
twice as long as broad. The nuclei of the cells of the lamellae may often be on 
the free edge of the cell, even forming projections on the surface ; a few nuclei are 
placed deeply in the cell. The roofs of the tunnels are often open, the cavity of 
the tunnel being thus in communication with the loose space beneath the epithelial 
lining of the oesophagus ; or a wide opening at the top of a tunnel may be spanned 
by a delicate fluff with nuclei in it. The tunnels are very low in segment xiv, and 
disappear before the end of the segment ; they die away by merging into the loose 
cells below the layer of oesophageal epithelium. 
The inner ends of the sinuses in the lamellae are always oval in section, not 
