338 EDITH M. PRATT. 
Each cell contains also a delicate reticulum of protoplasm 
and a deeply staining mucous secretion, which occupies the 
middle and upper portion of the cell, often in the form of a 
dense deeply staining reticulum. The secretion in some 
cases may be seen exuding through the outer wall into the 
stomodeum. In some instances the cells are almost empty. 
The mucous cells appear to be more numerous in tropical 
(figs. 5 and 6) forms than in the British species. 
(c) Nematocysts, similar to those occurring in the ten- 
tacles, are frequently imbedded in the outer ectoderm. 
(d) Scleroblasts with minute spicules are occasionally 
observed, but are never numerous. 
(ec) Columnar cells, usually with a single flagellum, 
more or less fill up the spaces between the superficial cells. 
(f) Interstitial cells, more deeply seated than any of 
the above-mentioned cells, are of varying shape, and may 
give rise to any of the superficial forms of cell. 
(g) Stellate cells, with long processes, are often attached 
to interstitial and other cells. They often extend into the 
mesoglcea, and have been described as nerve cells, and the 
processes as nerve fibrils. They have not, however, been 
experimentally shown to be nervous in function, but are 
identical in form, and probably also in function, with certain 
stellate cells which occur in the mesoglea (pp. 351—856), and 
are probably not ectodermic in origin. 
THE SIPHONOGLYPH. 
The siphonoglyph extends through the entire length of the 
stomodeum in Aleyonium, Sarcophytum, Lobophytum, 
and Sclerophytum, and is apparently lined throughout 
with flagella of uniform size. 
The stomodeum of Xenia, Ashworth (1898, p. 4438), is 
described as having a well-marked siphonoglyph, in which 
only the cells of the lower third bear long flagella. In 
Lemnalia (Bourne, 1900, p. 532) the siphonoglyph is present 
as a shallow ciliated gutter, but in some cases entirely 
