-2*7- 



Art. XXIV. — Descriptions of New, or Little Known, 



Polyzoa. 



Part IV. 



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



(WITH TWO PLATES.) 



-[Read 14th December, 1882.] 



Of the species of Retepora described in this paper, three are 

 new ; three others have already been briefly described by 

 me in the Society's Transactions for 1869. Two of these, 

 R. granulata and R. porcellana (as R. robusta), have since 

 been more fully described by Mr. Hincks, in a valuable 

 paper in the Annals and Magazine of Natv^ral History 

 for May, 1878. We have one or two other undescribed 

 species, as well as R. monilifero; (McG.), R. phoenicea (Busk), 

 jR. tessellatOj (Hincks), and what I believe to be R. cellulosa. 

 Of the last, I have not had an opportunity of examining 

 European specimens, but I expect to receive authentic ones 

 soon. 



Retepora serrata, n. sp. Fig. 4. 



Polyzoary expanded. Fenestra about the same width 

 as the interspaces, or slightly wider. Cells much elongated 

 separated by raised lines ; mouth nearly circular, or oval, 

 projecting forwards, with a small sinus below, and a fringe 

 of about twelve short, pointed processes arranged round the 

 margin. Ovicell rounded, smooth. A sessile avicularium, 

 with a long, narrow, pointed mandible at the bottom of each 

 fenestra, opening directly upwards. Back obscurely tuber- 

 cular, strongly vibicate. 



Of this species I have one perfect specimen, dredged off 

 Port Phillip Heads in about fifteen fathoms. The entire 

 specimen forms a small expansion three-quarters of an inch 

 in diameter, curved on itself on one side, where it is attached 

 to the calcareous tube of an annelid. The colour is leaden 

 grey. The cells are elongated, narrow, slightly expanded 

 upwards, separated by narrow raised lines. In the youngest 

 the mouth is smooth, the lower lip straight, slightly 



