LIMNOCNIDA TANGANICJE. 
93 
in the lining of the gastric cavity; moreover, he was not able 
to observe any traces of intra-cellular digestion in any of 
the cells of the endodermal epithelium. 
Again, previous authors have commented on the shortness 
of the manubrium, and pointed out that the space which should 
be the central cavity of the stomach is occupied by a great 
mass of jelly which forms the roof of this organ and almost 
blocks up the whole of the cavity of the sub-umbrella (cf. 
fig. 1). Referring to this point E. T. Browne (3) remarks : 
“ A similar kind of stomach is found in Mesonema 
pensile (Browne, 1904), a large medusa belonging to the 
Aequoriidae. In Mesonema the stomach has become quite 
rudimentary and the mouth cannot be closed. In Limno- 
cnida the abolition of the stomach is not carried quite so far, 
but to judge from the appearance of these specimens the 
mouth is incapable, owing to the shortness of the lower wall 
of the stomach, of completely closing up. 
“In the case of Mesonema I have suggested that the 
function of the stomach has been transferred to the canal 
system, and that the animal lives upon organisms of micro- 
scopic dimensions, such as unicellular Algae and Protozoa, 
which are driven by ciliary currents into the radial canals. 
Such organisms may also form the food-supply of Limno- 
cnida.” 
The histology of the man nb rial endoderm, described in the 
previous section of my paper, clearly shows that the lining 
epithelium of the manubrium is well adapted for digesting 
and absorbing food material in a perfectly normal manner. 
Perhaps the most interesting point in the histology of the 
endoderm is the unusually great development of goblet-cells 
in the oral region. 1 These must secrete a large quantity of 
some mucous substance which no doubt entangles within 
itself any small organisms which enter the mouth with 
1 Similar mucus-secreting cells occur in the oral regions of the 
digestive cavities of the Alcyonarians Xenia (Ashworth [9]) and 
Alcyonium (Pratt [10]). Duerden's paper on the role of mucus in 
corals (11) is also of great interest in this connection. 
