Paludicella is stated by Carter to have been found in Bombay, but probably what he really found was the young stage of V. bengalensis. A single species is known in Europe and N. America, namely P. ehrenbergi, van Beneden (=Alcyonella articulata, Ehrenberg).
I have examined specimens of all the species of this family as yet known.
Genus 1. PALUDICELLA, Gervais.
Paludicella, Gervais, Compt. Rend. iii, p. 797 (1836). Paludicella, Allman, Mon. Fresh-Water Polyzoa, p. 113 (1857). ? Paludicella, Carter, Ann. Nat. Hist. (3) iii, p. 333 (1859). Paludicella, Jullien, Bull. Soc. zool. France, x, p. 174 (1885). Paludicella, Kraepelin, Deutsch. Süsswasserbryozoen, i, p. 96 (1887). Paludicella, Loppens, Ann. Biol. lacustre, iv, p. 14 (1910).
Zoarium. The nature of the zoarium in this genus is well expressed by Ehrenberg's specific name "articulata," although the name was given under a false impression. The zoœcia arise directly from one another in linear series with occasional side-branches. The side-branches are, however, often suppressed. The zoarium as a whole is either recumbent and adherent or at least partly vertical.
Zoœcia. Although the zoœcia are distinctly tubular as a whole, two longitudinal axes may be distinguished in each, for the tip is bent upwards in a slanting direction, bearing the orifice at its extremity. The main axis is, however, at right angles to the dorso-ventral axis, and the dorsal surface, owing to the position of the aperture, can always be readily distinguished from the ventral, even when the position of the zoœcium is vertical. Each zoœcium tapers towards the posterior extremity. Parietal muscles are always present.
Fig. 36.—Structure of Paludicella ehrenbergi (A and B after Allman).
A=a single zoœcium with the polypide retracted. B=the base of the lophophore as seen from above with the tentacles removed. C=the orifice of a polypide with the collar expanded and the tentacles partly retracted. a=tentacles; c=collar; d=mouth; e=œsophagus; f=stomach; g=intestine; k=parieto-vaginal muscles; p=parietal muscles; o=cardiac part of the stomach; r=retractor muscle; s=funiculus.
Polypide. The most striking features of the polypide are the absence of any trace of a gizzard and the highly specialized form assumed by the cardiac part of the stomach. There are two funiculi, both connecting the pyloric part of the stomach with the endocyst. The ovary develops at the end of the upper, the testis at that of the lower funiculus.