Zoology.) NATURAL IIISToKY OF VTCTOlirA. [Polyzoa. 



Plate 108, Fig. 1. 

 CALPIDIUM ORNATUM (Busk). 



Description. — Polyzoary consisting- of broad, closely set branches; internodes 

 of three, or occasionally of two, laterally coalescent cells; cells very large, with five 

 large fenestra on each ; posterior surface with a central, thickened band, correspond- 

 ing to the middle of the median cell, and two pairs of transverse bands going at 

 right angles from this, the upper again dividing. 



Reference.— Busk, Brit. Mus. Cat. Mar. Pol, p. 15, PI. XII. and XIII. 



Port Phillip Heads, seemingly very rare. 



The only specimen I have, which I dredged in about 1 5 fathoms, 

 forms a thick tuft, about 3 inches high. The branches are broad, 

 closely set, fiat, almost penniform in arrangement. The internodes, 

 which are broad and urn-shaped, usually consist of three coalescent 

 cells, but occasionally one lateral is wanting. At each upper 

 angle, whether the internode consists of two or three cells, is a 

 large avicularium. Almost the whole front of each cell is occupied 

 by 5 fenestras, separated by raised bands. The posterior surface is 

 marked by a vertical, thickened band, corresponding to the central 

 line of the median or primary cell ; from this two pairs of bands 

 are given off at right angles, the upper of which again gives oft' 

 another branch, which ascends vertically and then turns horizontally 

 outAvards. 



The ovicell, for specimens of which I am indebted to Mr. J. B. 

 Wilson, very much resembles that of Catenicella plagiosfo?iia. 

 It is terminal, of great size, equalling in width the preceding 

 tricellular internode, with the summit of the middle cell of which 

 it is connected by a short tube. It is obscurely triangular in 

 outline, with the apex produced into a simple, sharp, or bifid 

 process. On the front is a prominent vertical ridge. The 

 opening is very wide, looking downwards and slightly forwards; 

 the margin is thickened, especially anteriorly, where it forms a 

 broad collar. A specimen, which is unfortunately somewhat 

 damaged, mounted in balsam, shows a shallow operculum with its 



Vol. II.— Decade XL—/. ~ 33 ~ 



