Zoology.'] NATURAL HISTORY OF VICTORIA. [Poli/zoa. 



The very youngest zooecia have the mouth straight and entire 

 below, but, in almost all, a process of the peristome is seen rising 

 on each side, eventually meeting in the centre and leaving a round 

 opening which in time becomes filled in. Below the mouth a 

 process rises on one side, extending upwards and to the opposite 

 side, with a considerable avicularium on its summit, the edge of 

 the rostrum being serrated. In some marginal zooecia this process 

 is very large and directed upwards, the avicularium situated 

 obliquely on the summit. The older zooecia vary much in form, 

 being usually short and oblique or nearly erect. The sub-oral 

 pore of the peristome can frequently still be seen, and the peristome 

 is also, in some cases, produced above in a hooded manner, like a 

 commencing ocecium, or it may be almost tubular with a slit in the 

 lower edge. The aviculiferous jn'ocess below the mouth is usually 

 of small size, but is occasionally enormously developed, so as to be 

 larger than the zocecium itself. There are numerous vicarious 

 avicularia, with spatulate mandibles, much raised, the point of the 

 calcareous eminence frequently projecting over part of the neigh- 

 bouring: zooecia. 



Explanation of Figures. 



Plate 128 — Fig. 2, specimen, natural size. Fig. 2a, portion of central part of same, 

 magnified. Fig. 2b, marginal zooecia. Fig. 2c, single zooecium, showing the sub-oral pore and 

 short aviculiferous process. Fig. 2d, enormously developed sub-oral avicularium, showing the 

 broad mandible, serrated rostrum, and mouth of the zooecium (in the figure beneath the avicu- 

 larium). 



Plate 128, Fig. 3. 

 CELLEPORA TRIDENTICULATA (Busk). 



Description. — Zoarium small, encrusting-. Zooecia immersed, irregular ; sur- 

 face granular; mouth straight below, rounded above, with 2-4 long, slender spines 

 articulated above, and 3 small denticles (the middle hammer-shaped) within the 

 lower margin. A minute avicularium, with a semicircular mandible, on a slightly 

 elevated sub-oral rostrum. 



Reference. — Busk, Challenger Polyzoa, p. 198, pi. xxix., fig. 3. 



Port Phillip Heads ; Warrnambool, Mr. Watts. 

 Of this species I have only two or three minute specimens, the 

 only perfect one of which is that figured. It seems to be identical 



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