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Genus V. Plumatella, Lamarck, 1816. 



Name. — A diminutive noun, formed from pluma, a feather, in allusion to its plume-like 

 crown of tentacles. 



When Vaucher, in 1804, added, under the name of Tubularia lucifnga, a supposed new 

 species of fresh-water Polyzoa to those previously known, all these animals, with the exception 

 of the xMcyonmm fluvlatile of Bruguiere, and the Kleiner Federhusch Polyp of Eosel, for which 

 Cuvier had constituted a genus under the name of Cristatella, were placed in the genus Tubu- 

 laria, along with numerous marine polypes of a totally different organization. The unzoolo- 

 gical nature of this association was apparent to Bosc, who, in 1804, pointed out the necessity 

 of viewing the so-called Tubularias of fresh water as a distinct generic group, of which he gave 

 the characteristics, but which he neglected to name, and it was reserved for Lamarck, by 

 naming Bosc's genus, to confer on it a fixed and definite place in our systems. The name of 

 Plumatella was that which Lamark gave to this group, but as it included the " Polype a 

 Panache," a polyzoon whose organization does not admit of a generic association with the 

 others, it has since been found necessary to restrict the genus Plumatella as established by 

 Bosc and Lamarck, and to constitute a separate genus for the " Polype a Panache." 



Except in the condition of the dermal system, the structure of Plumatella differs in no 

 essential point from that of Alcyonella. This system, however, in the coalescence of the tubes 

 into a common mass in Alcyonella, while they remain totally distinct in Plumatella, presents 

 us with a difference which I believe to be of sufficient importance to justify us in placing the 

 two forms in separate generic groups.* 



The coenoecium in Plumatella consists essentially of a linear, more or less branched series 

 of tubular cells of membrano-corneous consistence, each springing from its predecessor, and 

 constituting a short ramulus, which is terminated by the orifice destined for the egress of 

 the polypides. In some species the cells are nearly cylindrical, in others they are claviform, 

 and when the latter figure occurs, especially in connection with short cells, a more or less 

 moniliform, or concatenated appearance is presented by the coenoecium. In most of the 

 species, perhaps in all, transverse septa or diaphragms occur near the origin of certain cells 

 when complete, separating the cavities of these cells from those of the neighbouring ones. 

 They, however, are very frequently incomplete, admitting of a free communication between 

 neighbouring cells, and in many cells are even totally absent. In some species they occur at 

 distant and irregular intervals, and may be easily overlooked, while in others {P. coralloides) 

 they exist with almost as much regularity and completeness as in Paluclicella. The first 

 instance in which 1 became aware of the existence of these septa was in Plumatella coralloides, 

 where they occur with singular regularity and distinctness. So striking, indeed, was the 

 character thus presented, that 1 thought it of sufficient importance to entitle this species to the 

 rank of a distinct genus. Further investigation, however, rendered apparent the presence of 

 similar septa in other species, but occurring frequently at such distant intervals in the 

 tubes, and with so much irregularity, as to deprive this character of that importance which one 



* See above, p. 8G. 



