BRYOZOA 



tubular portion of the zoœcia is quite free. Probably this is the most important character 

 of the genus Bicellaria. 



Bicellaria is well représentée! in the southern hémisphère, but only by very few species 

 in the northern. 



Habitat. — Bass's Strait (Busk) ; Victoria (MacG.). 



Exp. Antarct. Belge. 



N 1068. Straits of Magellan. Sur la carapace d 'Eurypodius Latrcilii. 



Flustra flagellata sp. nov. 



fPl. II. figs. la, b 



Zoarium unilaminate. Zoœcia elongate, contracted below, with a vibracular chamber 

 at the proximal end of each zoeecium, with very long vibraculae. There are about 6 latéral 

 rosette plates, and the distal wall has two pores, with sometimes also two or three small 

 ones between them. 



There is only a small fragment, in which there are no polypides, although ail the 

 muscles remain in the vibracular chamber. In two cases where two zoœcia grow from an 

 older one, there is a vibraculum at the base of each, and from this fact and the position 

 of the distal rosette plates, we speak of the vibraculum being at the proximal end of the 

 zoœcium. This is the only case of F lustra having vibracula, but there does not seem to 

 be any reason for generic séparation on that account. 



Calvet (') in a very important work dealing with the structure of the Ectoproct 

 Bryozoa says : « Les aviculaires et les vibraculaires ne sont que deux formes d'une même 

 individualité, ne se distinguant entre elles que par la longueur plus ou moins grande de la 

 mandibule et le développement plus ou moins réduit du bec. » I certainly cannot go as far 

 as Calvet, although of course there is much similarity in the two organs with probably a 

 similar origin. The différence between the two is, in my opinion, quite indépendant of the 

 length of the setae, and is to be looked for at the base and in the muscular attachment. 

 The base of a vibraculum is unsymmetrical, and besides, the central articulate portion has 

 various protubérances to which muscles are attached, thus permitting movement in ail directions, 

 whereas the base of the avicularium is symmetrical and there is only movement in one 

 direction. 



I figurée! the base of the vibraculum of Cribrilina latimarginata Busk ( 2 ) in m}' « Supple- 

 mentary Challenger Report », and then referred to the différence in structure. Scrupocellaria, 

 Selenaria, Cupularia, Caberea, &c. hâve true vibracula, whereas the extremely long mandible 

 of Diporula Hyndmanni, var. ensiformis Hincks has a symmetrical base and is part of an 

 avicularium. It is true that many avicularia with long mandibles hâve been wrongly called- 

 vibracula, and further Smitt's figure of the vibraculum of Scrupocellaria scruposa L., which 

 is incorrect has been reproduced by Hincks and others, and has no doubt led to some 

 confusion. 



(1) Louis Calvet, Contr. à l'hist. nat. des Bryozoaires Ectoproctes marins, 1900, p. 440, etc.. 



(2) YYaters, Zool. Chall. Exp., vol. XXXI, pt. LXXIX, p. 22, pi. I, ùg. 12. 



