114 PALUDICELLA EHRENBERGI. 



1813. Fuludicella articulaia. Thompson, Rep. Brit. Assoc, p. 285. 

 1844. Paludicella arliculata. AUmann, Anu. Nat. Hist., vol. xiii, p. 331. 



1847. Paludicella arliculata. Jolinston, Brit. Zoopli., 2d edit., p. 105, fig. 77, 



p. 406. (Original figure.) 



1848. Paludicella Eltrenberyi. Van Beneden, Reclierches sur les Bryoz. fluv. de 



Belg., p. 27, Mem. de I'Acad. Ro}-. de Belg. 

 1848. Paludicella E/irenberf/i. Dumortier et Van Beneden, Hist. Nat. des Pol. 

 Comp. d'cau douce, Mem. servant de Complement au tome xvi des Mem. 

 de I'Acad. Roy. de Brux. (Original figures.) 



1850. Paludicella procumbens? Hancock, Ann. Nat. Hist., 2d series, vol. v, p. 201, 



pi. 5, figs. 1, 2, and pi. 4. (Original figures.) 



1851. Paludicella elongala? Leidy, Proc. Acad. Nat. Sci. of Philadelphia, vol. v, 



p. 321. (Original figure.) 



Tconof/raplii/. — The original figures are those of Van Beneden (Bui. Ac. Brux.), Van 

 Beneden (Mem. de I'Ac. Brux.), Gervais, Allman, Johnston, Hancock, and Leidy. 



Habitat. — On submerged stones in still and slowly running water. Eminently Ught- 

 shunning. 



Localities. — British: Regent Canal, London; Chelmer Canal, Essex; Grand Canal, 

 Dublin ; Union Canal, Edinburgh. G. J. A. — Lough Erne, Ireland. Mr. Wm. Thompson. — 

 Bromley Lough, Northumberland. Mr. Hancock. 



Foreiffu : Lake of Lucerne, Lake of Zurich, Lago di Como, and Lago di Lugano. G. J. A. 

 — Near Paris. Gervais. — Belgium. Dumortier and Van Beneden. — Prussia. Ehrenberg. — 

 Near West Point, in the United States ; abundant. Brof. Bailey. 



The specific name articulata, originally applied to this species by Ehrenberg, was 

 sufficiently significant, so long as the animal was described as a species of Alcyonella ; it is 

 now, however, quite inapplicable, for it possesses no specific meaning whatever, being 

 expressive of one of the most striking characters on which the (/enus formed for it has been 

 founded. \, therefore, entirely agree with M. Van Beneden, in admitting the necessity of 

 changing the original specific name, and willingly adopt that of Ehrenberyi, proposed for it by 

 the learned Belgian naturalist in honour of its discoverer. 



P. Ehrenhergi is very widely distributed, and we can scarcely account for its having so 

 long escaped notice, except by supposing that its resemblance to some of the confervoid algae 

 caused it to be overlooked. The ccenoecium is partly free, partly adherent. The adherent 

 portion extends over the under surface of stones as a branched confervoid growth, the 

 branches being given off either opposite to one another in pairs, or else singly, the develop- 

 ment of the opposite branches being in the latter case suppressed. Besides the portion 

 which thus continues closely adherent to the supporting surftice, numerous branches remain 

 quite free, growing in luxurious specimens frequently to the length of two inches, and being 

 themselves ramified in a manner quite similar to what occurs in the adherent portion. 



The structure of both adherent and free portion is similar, every branch consisting of a 

 series of symmetrical clavate cells, each of which is attached by its narrow extremity to the 

 wide extremity of the cell below it, from which its cavity is separated by a perfectly formed 



