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THE VOYAGE OF H.M.S. CHALLENGER. 
a strong resemblance to Adeona appendiculata, which is however more decidedly cordi- 
form at the base and has a much longer rigid calcareous stem, but the characters of the 
zooecia themselves differ very widely. The lateral papillary eminence below the 
mouth, which is seen in several other species, is wanting in Adeona appendiculata, and to 
judge from Mr. Macgillivray’s figures the frontal avicularia in Adeona grisea are much 
smaller, and he makes no mention of the marginal avicularian cells, which form a 
marked feature in Adeona appendiculata. 
As regards colour, again, which is a very important character in the Adeonese, although 
Mr. Macgillivray does not notice it in his description, there is a very striking difference 
between the two. To judge from several fine specimens of what I take to be the Adeona 
grisea of Macgillivray lately sent by Mr. Wilson to the British Museum, the colour of 
that species is nearly black, whilst in the beautifully perfect and well-preserved specimen 
in the Challenger Collection the colour is that of a lightly baked biscuit. In Adeona grisea, 
also, the mandibles of the frontal avicularia are much smaller and nearly triangular, with 
an obliquely curved point, and those of the avicularian cells of the same character only much 
larger, and not at all like the marginal avicularia of Adeona appendiculata. Adeona grisea 
lias distinct though delicate elliptical opercula both of the zooecial and ocecial cells. 
But another character which would alone suffice to distinguish Adeona appendiculata 
is the presence of the intercalated minute avicularia among the cells, and apparently not 
always if ever connected with any individual zooecium. This character does not appear to 
exist in any other species with which I am acquainted. As the species is imperfectly 
figured in the Plates, woodcuts are given one ot the organism, natural size, the other of 
the chitinous parts. 
