242 M. Lacaze-Duthiers on the Antipatharian Genus Gerardia. 
states of preservation ; but, at the same time, everything is ex- 
plained when we examine living animals, and see what they be- 
come by desiccation. 
The Antipathes glaberrima of Esper and Lamarck is very distinct 
fromthe species of Antipathes proper; the genus Leiopathes of Gray 
may therefore be adopted for it. But we must avoid regarding 
as belonging to it the polypary of Gorgonia tuberculata, Lamk., 
whether denuded or covered with sarcosoma, as has been done 
by J. Haime. On the other hand, this Lamarckian species re- 
presents a very clearly defined type, which must be regarded as 
a genus for which a name is necessary; for it is not an Anii- 
pathes, and still less a Gorgonia; and its very smooth polypary, 
examined by itself, has alone led to its being looked upon as a 
species of Leiopathes. 
The new genus Gerardia which I propose presents a set of 
positive characters which distinguish it at once from Antzpathes, 
Leiopathes, and Gorgonia: its validity does not appear to me to 
be doubtful. As to the species, it will be convenient to retain 
for it the name given to it by Jules Haime. 
At the commencement of its development, Gerardia Lamarcki 
spreads its zoanthodema, formed entirely of sarcosoma, upon 
other polyparies; at this time it is perfectly parasitic. Sub- 
sequently it covers these foreign bodies with its own polypary, 
and produces branches and twigs; from this period it becomes 
independent, and its parasitism ceases. This is the reason why 
we find in the centre of the thick trunks of its polypary the 
slender stems of Muricea placomus, Gorgonia subtilis, &e. A 
Crustacean which lives parasitically in the soft tissues sometimes 
has its carapace covered by the horny deposits of the Gerardia. 
The egg-cases of Sharks and Rays, the suspensory filaments of 
which have seized its zoanthodemata, are first of all covered by 
expansions of its sarcosoma, and then taken bodily into its poly- 
pary. It is only by long-continued researches that I have been 
able to recognize the true part that must be ascribed to this 
parasitism. 
The anatomy of Gerardia Lamarcki possesses great interest in 
a scientific point of view. The bodies of the animals, like the 
intermediate tissue that unites them, are formed of two layers 
of cells: the inner one, which is yellow and granular, lines all 
the cavities, and is covered with vibratile cilia; the external 
layer, which is nearly colourless, is contractile and filled with 
bundles of nematocysts. 
The polypes resemble young Actinie ; they have twenty-four 
simple tentacles, arranged in two rows round the mouth, and 
the oblong and turned-up lips of the latter form a central 
mamilla. The number of tentacles is a multiple of six, and 
