. Contributions to the natural history of the United States of America. Zoology; Chelonia (Genus); Ctenophora; Cnidaria; Animals. 50 ACALEPIIS IN GENERAL. Part I. Fhj. 2C. compound communities of Ilydioids arc attached to the ground, those of Siphono- phorai are free; but this is not a. character exclusively peculiar to them, for among the Polyps we have also free communities belonging to the same order as others that are immovaljly attached to the ground. Such are the genera Renilla, Penna- tula, Virgularia, Veretillum, etc., which are inseparable from the genera Gorgonia, Alcyonium, Xenia, T
. Contributions to the natural history of the United States of America. Zoology; Chelonia (Genus); Ctenophora; Cnidaria; Animals. 50 ACALEPIIS IN GENERAL. Part I. Fhj. 2C. compound communities of Ilydioids arc attached to the ground, those of Siphono- phorai are free; but this is not a. character exclusively peculiar to them, for among the Polyps we have also free communities belonging to the same order as others that are immovaljly attached to the ground. Such are the genera Renilla, Penna- tula, Virgularia, Veretillum, etc., which are inseparable from the genera Gorgonia, Alcyonium, Xenia, Tubipora, etc., or at least Ijelong to one and the same order. In these locomotive Halcyonoids the individual Polyps are identical among them- selves, but grouped together in the most diversified ways, varying in that I'espect quite as much among themselves as the fixed Halcyonoids. In Pennatula and Virgularia they form i-egular rows upon the two sides of a feather-like stem, in Veretillum they are scattered around a cylindrical stem, in Eenilla they are arranged in symmetrical lines upon the surface of a kidney-shaped disk. And yet these connnunities move and act as one individual. I have frequently seen Eenilla, which is our only genus of free Halcyonoid Polyps, move slowly about in tlie sand, its stem Ijuried in a vertical position with the disk spread horizontally. Now, if I have succeeded in showing that, l>y their structure, the so-called Hydroid Polyps are not Polyps, but Acalephs, and if I should also succeed in showing that the different kinds of individuals forming the communities of 8i[)lionophoraj have the same structure as the Hydroids, and jn-esent everywhere, in all their parts, special homologies with the Hydroid Polyps and naked-eyed Meduste, without even exhiluting one of the peculiar char- acteristics which distinguish the true Polyps from the Hy- droids, I should then have proved that the Siphonophora) are reall)'^ Hydroid Acalephs, and not Polyps, as Kijl
Size: 950px × 2632px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdeca, booksubjectanimals, booksubjectzoology
