158 Mr. H. J. Carter 07i Parasites of the Spongida, 



pieces of the seaweed on which G. compressa chiefly grows 

 here, it is desirable to free the specimens as much as possible 

 from the Alga, lest, under confinement, the crustaceans issue 

 from their nests in the latter, where they dwell in great abun- 

 dance, make an onslaught on the Grantias, and destroy the 

 greater part of them. 



CiRRIPEDES. 



The Balanoid Cirripedes, whose embryos are so abundant 

 that they almost cover every thing on the rocks here, together 

 with the rocks themselves, could hardly be expected to refuse 

 the surface of the Spongida ; and hence, perhaps, they are the 

 most common parasites of all ; for, with the exception of the 

 fleshy sponges [Carnosa) and the calcareous ones {Calcarea), 

 they make use of every other kind of sponge, becoming, as 

 they increase in size, overgrown by the sponge itself, whether 

 the latter is kerataceous or vitreous, so as to form wart-like 

 excrescences with a hole in the summit for the projection of 

 the cirri. The species appear to vary in the same as well as 

 in different localities ; and the term " Acasta " has been ap- 

 plied to the whole group by Leach. 



AcTiNOzoA OR Polyps. 



In all parts of the world sponges are more or less infested 

 by polyps, chiefly on the surface, which may be single, double, 

 concatenated, or grouped, isolated or aggregated, sunk to the 

 level of the surface of the sponge which they may infest 

 without scleroderma, or with it in the scleroderma on the sur- 

 face of the sponge, or pendent from the scleroderma ; and all 

 belong to the Zoanthida3 = Palythoa, Laraour., = Zoantha of 

 De Blainville. 



Of those on the sponges of the Antilles, Duchassaing de 

 Fontbressin states : — 



" Les Zoanthes, les Mamillif^res et les genres voisins sont 

 littoraux ; cependant il y a des exceptions pour quelques-uns 

 des ces etres, comme le Zoanthus parasiticus, le Gemmaria 

 Swiftii et les Rergia, qui toutes sont parasites des Sponges, et 

 que j'ai recueillies par une profondeur variant entre 2 et 8 

 metres. Ces espfeces ne se trouvent jamais que fix^es sur les 

 Spongiaires ; elles ne se rencontrent sur aucune autre esp^ce de 

 corps marins." (' Revue des Zoophytes et des Spongiaires des 

 Antilles,' par M. P. Duchass. de Fontbressin, 1870, p. 22.) 



Such are the words of this naturalist, who, with M. 

 (afterwards le Chevalier) G. Michelotti, published copiously 

 illustrated works on the corals and sponges respectively of 



