242 M. Lacaze-Duthiers on the Antipaiharian Genus Gerardia. 



states of preservation ; but, at tbe 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 

 from the species of Antipathes proper; the ^enns 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 Anti- 

 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 Antipathes, 

 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, &c. 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 Actinise ; 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 



