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Art. XVII. — Descriptions of New, or Little Knovm, 



Polyzoa. 



Part III. 



By P. H. MacGillivray, M.A., M.R.C.S., F.L.S. 



[Read 12th October, 1882.] 



Membranipora serrata, M'G. Fig. 5. 



In a paper communicated in December, 1881, I figured 

 this species which I had previously described, and also 

 described and figured a seemingly distinct form as M. 

 acifera. I have since then dredged a specimen at Port 

 Phillip Heads, which shows them to belong to the same 

 species. In some parts at the centre and circumference 

 of the colony the cells are wide, the margins either 

 unarmed or with one or more sharp uncinate spines ; in 

 other cells the spines are forked, or broad and serrated, 

 and in many so large that those of opposite sides inter- 

 digitate, and occasionally coalesce. 



Cribrillina setirostris, n. sp. Fig. 3. 



Cells distinct, elongated ; surface thickly covered with 

 round or pyriform white-bordered pores, frequently 

 arranged in irregular single or double transverse rows ; 

 mouth arched above, nearly straight below, with a slightly 

 thickened margin ; an avicularium at the base of the cell 

 with a very long setiform mandible directed close up one 

 margin of the cell. 



Port Phillip Heads. Dredged by Mr. J. B. Wilson and 

 myself. 



Schizoporella Ridleyi, n. sp. Fig. 1. 



Polyzoary encrusting ; cells rhomboidal or elongated, 

 in radiating linear series, separated by slightly raised 

 margins; surface when young smooth ; when older deeply 

 areolated at the edges; mouth semi-circular above, straight 

 below, with a small rounded sinus ; below the mouth a 

 small vertical elliptical avicularium on an elevated part 

 of the cell ; ovicell rounded. 



