256 



ziemlich ansehnlichen Platten, die, gleich der Achse, von 

 zahlreichen fest aneinander gefügten kleinen Kieselkörnern 

 (ovisacs Gr.) gebildet sind. Gray in der Proceed. Zool. 

 Soc, 1867. p. 627. mit Holzschnitt. 



Nachträglich wird (ibid. 1868. p. 575—579, mit Holz- 

 schnitt) von unserem Verf. der Gruppe der Hornschwämme 

 noch die Familie der Gera teil ad ae hinzugefügt, die auf 

 zwei neue australische Formen, Ceraiellafusca undDe- 

 hitella airorubens, gegründet ist. Beide gleichen durch 

 schlanke Form, baumartige Verästelung und stachlige Be- 

 schaffenheit einer Gorgonide, und zwar so vollständig, 

 dass es erst durch nähere Analyse des Skelets möglich 

 wurde, die — seitdem auch von Wright, quarterly 

 Journ. micr. sc. 1870. p. 90, bestätigte — Natur derselben 

 zu erkennen. 



Die Beschaffenheit dieser beiden merkwürdigen Schwämme er- 

 hellt am besten vielleicht aus der folgenden Diagnose: 



Gerat ella Gr. Sponge irregularly dichotomously branched, 

 more or less expanded on a plane from a single base; of a dark 

 browu colour. of a uniform, hard. horny snbstance; stem hard, dark 

 brown, solid; base dilated. rather compressed, of a uniform rigid 

 somewhat spongy texture, with a velvety surface, which is formed 

 of an abundance of very minute, cylindrical, tortnous grooves. The 

 branches and branchlets tapering, formed of a very large quantity 

 of nearly parallel, paler brown, projecting, horny points, divergent 

 at the ends, and producing a spinulose surface. The branchlets 

 tapering to a point. with a series of acute divergent tufts of spicu- 

 les an each side (oscules or cells), with a small circular mouth below 

 the produced acute outer edge of the tufts of spicules ; one of the 

 lufts is placed at the end of the branchlet ; and the tufts seem to 

 be produced at the base of the previously formed tufts. 



Dehitella Gr. Sponge or coral dichotomously branched, 

 expanded, growing in a large tuft from a broad, tortuous, creeping 

 base, of a dark brown colour, and uniform hard rigid substance. 

 Stem hard, cylindrical. covered with tufts of projecting horny spi- 

 nes on every side. those ou the branches often placed in sharp- 

 edged, narrow transverse ridges; those of the upper branches and 

 branchlets close, but isolated, and divergent from the surface at nearly 

 right angles. This genus is distinguishable from Ceratella by great 

 thickness and cylindrical form of the stem. by the more tufted and 

 irregulär manner of growth and by the tufts of spicules (oscules or 



