Zoology.'i NATURAL HISTORY OF VICTORIA. [Po/yzoa. 



Description. — Zocecia ovate or quadrate; separating margins thick and 

 prominent, frequently raised into a clavate process on each side of the mouth ; 

 surface smooth, g-ranular or punctate, frequently with a distinct round foramen on 

 each side. Mouth arched above, lower lip thickened and usually finely crenulated. 

 Ooecia large, convex, prominent or subiuimersed, smooth, or tubercular, or umbonate, 

 or slightly carinate. Avicularia small, with triangular mandibles, situated on 

 separate tracts at the bases of zocecia. 



References. — Memhranipora coriacea, Busk., Brit. ilus. Cat. Mar. PoL, ii., 67, 

 pi. Ixxiii., figs. 4-5; Micropora coriacea, Hincks, Brit. Mar. Pol., p. 174, pi. xxiii, 

 figs. 5-7. 



Common on shells aud stones. 



This species varies a good deal. The anterior surface is 

 smooth or granular and frequently has a large round pore on 

 each side, genei-ally toAvards the mouth. The separating margins 

 are occasionally (in European specimens usually) raised into a 

 small clavate boss on each side of the mouth. The ooecia are 

 mostly subimmersed, but are sometimes quite prominent. 



A very marked variety which I have described (Trans. Roy. 

 Soc. Vict., 1886) as angusta is not uncommon. The zooecia 

 are very long and narrow, quach'ate ; the margins very prominent 

 and crenulated ; the surface granular. There are no distinct 

 foramina, but a depression in some cases gives an obscure appear- 

 ance of such. The lower lip is thick and pouting. The ooecia 

 are sub-immersed, usually without any elevation but occasionally 

 with a slight knob or ridge. The whole zoarium is silvery and 

 frec[uently only loosely adnate. Steganojjorella dongata (Hincks, 

 Ann. and Mag. Nat. Hist., Nov., 1880) fi*om Afi-ica very much 

 resembles this form. Mr. Waters also (Ann. and Mag. Nat. 

 Hist., July, 1889) refers some specimens from Port Jackson to 

 the same species as Micropora dongata, stating that in examin- 

 ing a series there is little dift'ereuce between it and 31. coriacea. 

 He also mentious that in some of the zooecia the marginal 

 openings (opesiules of JuUien) are not to be seen while in others 

 there are more than one on each side. 



Explanation of Figures. 



Platk 19G. — Fig. 4, group of zoa'cia friim a colony wiih the anterior surface nearly 

 smooth, the lateral pores large, the margins not raised at the oral apertures and the ooecia 

 prominent. Fig. 5, part of another colony, having the surface granular and punctate, the 

 margins forming clavate knobs and the ootcia umbonate. Fig. (>. var. aixjiista, showing the 

 elongated quadrate zooecia, the thick crenulated margins, the pouting mouth, aud subimmersed 

 occcia. 



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