A MONOGRAPH OF THE TERTIARY POLYZOA OF VICTORIA. 103 



Porina, 2>' Orhkjmj. 



Zoarium encrusting or erect and uni- or bilarainate or cylindrical. Zoojcia \\\W\ 

 the thyrostome subcircular, the peristome produced and having one or more suboral 

 pores opening into its cavity above the operculum. 



The essential character of this genus is the presence of one or more suhoral 

 pores opening into the peristomial chamber in front of the operculum, and so 

 difPering from the special pores of the Microporellidoe, which open into the body 

 cavity. 



1. P. gracilis, Milne Edwards, sp. PI. XIV., figs. 21-24. 



Eschara gracilis, Milne Edwards, Sur les Eschares, p. 28 ; Busk, E.M.C., II., 

 91 ; C.P., Pt. I., lil ; McG., P.Z.V., AS ; Cpllaria coronafa, Reuss, Eoss. Polyp, der 

 Wien. Tcrt., p. 62 ; Forina coronata, Waters, Q.J.G.S., 1881, p. 333 ; Spiropori na 

 vertehralis, Stoliczka, Eoss. Bryoz. der Orakei Bay, p. 106; Forliia Dieffeuhachiaua, 

 id., p. 135 ; Leptohothrus spenceri, T. S. Hall, T.R.S.V., Oct., 1892, described as a 

 Stylasterid. 



Zoariuni encrusting, lobed and bilaminate, or cylindrical. Zocecia mostly 

 indistinct in the crustaceous and lobed form, more distinct in the cylindrical, surfnce 

 closely pitted ; thyrostome circular or wider than high ; peristome thick on od and 

 slightly raised, or much elongated and tubular, in both cases with a circle of small, 

 round, frequently elevated avicularia on its free edge ; peristomial pore immediately 

 below the thyrostome or a short distance down the zoarium ; small avicularia similar 

 to those round the thyrostome scattered irregularly over the zoarium, and occasion- 

 ally a few large spatulate ones. 



The following varieties may be indicated, taking the lobed form as ilie 

 typical : — 



Var. {a) dieffenhachiana, Stol. Branches cylindrical ; zooecia irregularly 

 arranged. 



Var. {h) rertebralis, Stol. Branches cylindrical ; zooecia arranged verticillately. 



Var. ((?) tubidifera. Branches cylindrical, slender ; zorecia with tlie peristome 

 much produced and tubular. 



S.P. ; M.C. ; B. ; C.B. ; Belm. ; M. ; C.C. (W.) A common living Australian 

 species. 



The lobate form is that usually found recent, while the great majority of the 

 fossil specimens an^ cylindrical. 



