^oohgi/.'] NATURAL HISTORY OF VICTORIA. \Polyzoa. 



Form umbonata (P. McG.). 



Plate 97, Figs. 1-3. 



Description. — Polyzoary foliaceous, expanded, or convoluted; fenestras elliptical, 

 narrower than the intei'spaces ; cells quadrate or ovate, separated by much raised 

 margins; surface granular, giassy; mouth sloping- obliquely backwards ; in young- 

 cells lower lip nearly straight or hollowed, entire, thin ; in older with a loop-shaped 

 notch, at one ang-le of which is an avicularium; this notch frequently bridged over, 

 leaving- a small foramen, also sometimes obliterated, in the latter case the lip being- 

 thickened, and at its junction with the lateral margins projecting- slightly, giving 

 orig-in to slender, jointed spines; in many of the older cells these spines are very 

 thick and telescopic in appearance, and frequently confined to one side; avicularia 

 very varied, frequently a semilunar one above a fenestra, and also often one with 

 a long-, narrow mandible closing- in a bidentate rostrum, opening- horizontally inwards 

 on the edg-e of a fenestra ; ovicell prominent, the vertical band ending- in the base 

 of a sharp, smooth, umbonate process ; posterior surface strongly vibicate, with 

 numerous, small, round avicularia, especially about the edg-es of the fenestras. 



Port Phillip Pleads, 15 fathoms. 



This form, which is of comparatively small size, is distinguished 

 by the much-raised margins of the cells and the peculiar umbonate 

 process on the ovicell. These characters are usually so marked 

 that it might seem necessary to constitute a distinct species. In 

 some cases, however, the umbonate process scarcely exists, and the 

 vertical band is little more raised than in sinuata. Young cells of 

 munita also frequently have the margins much raised. 



Explanation of Figures. 



Plate 96. — Fig. 1, specimen R. monilifera, normal form, natural size. Fig. 2, young 

 marginal cells, from a similar specimen, magnified. Fig. 2a, other cells from the same specimen. 

 Fig. 2i, older portion, showing ovicells and avicularia. Fig. 3, portion of var. sinuata, showing 

 large sinus, oral avicularia, and spiues. Fig. 4, specimen of Jl. monilifera, form munita, natural 

 size. Fig. 5, young cells of var. lunata. Fig. 5a, another portion of the same specimen, showing 

 a large avicularium. Fig. bb, single cell and avicularium of same specimen. Fig. 6, small portion 

 of another specimen, showing ovicells. Fig. 7, small portion of var. acutirostris, to show large 

 avicularium and structure of the moiith. Fig. 8, small portion of another specimen, showing 

 both semicircular and long-pointed avicularia. 



Plate 97. — Fig. 1, specimen of R. monilifera, form jtmbonata, natural size. Fig. 2, small 

 portion, magnified. Fig. 2a, ovicell, partly in profile, to show prominence of umbo. Fig. 3, 

 young cells. Fig. 3a, two cells of same specimen, showing the long, jointed spines. 



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