THORNELY— MARINE POLYZOA OF THE INDIAN OCEAN 147 



52. Lagenipora spinulosa, Hincks, Ann. Mag. Nat. Hist., ser. 5, xiii, 1884, p. 210. 

 Amirante, 38 fath. Small, erect colonies, growing on Nellia oculata, 



53. Retepora monilifera, MacGillivray, var. nov., Trans. Phil. Inst. Vict., iv, pt. 2, 

 p. 168; MacG., Prod. Zool. Vict. Dec. x, p. 19. 



The representatives of this species in the present collection do not correspond exactly 

 with any of MacGillivray's various forms, but have usually the following characters : a 

 centi'al pore, moi'e or less complete ; the edge of the lower margin of the orifice sometimes 

 crenulated ; an avicularium to one side of the pore and close up to the margin, not always 

 present, sometimes another below this one, and there are long pointed avicularia situated 

 at the bases of some of the fenestrse, the mandible when at rest lying between the two 

 points of the beak. There are no avicularia on the dorsal surface. Goecia have a long 

 vertical band and a shorter horizontal one, an avicularium on one or both sides of the 

 vertical band. These characters are more or less constant on the many colonies and 

 fragments of colonies in the collection. 



Seychelles, 39 fath. ; Amirante, 29 — 30 fath. ; Cargados, 28 fath. ; Providence, 

 50 fath. ; Saya de Malha, 47 fath. ; Diego Garcia, 12 fath. 



54. Retepora porcellana, MacGillivray, Trans. Roy. Soc. Vict., ix, p. 140, 1868 ; 

 MacG., Prod. Zool. Vict. Dec. x, p. 15. 



Seychelles, 39 fath.; Amirante, 25 — 30 fath. ; Saya de Malha, 150 fath. ; Cargados, 

 28 fath. 



55. Retepora denticulata, Busk, Report Challenger Exp., x, pt. xxx, p. 109. 



There is a colony an inch in height. There are no barren trabecuhe, the zoarium is 

 dichotomously branched, the tips of the branches bending over and uniting. The zooecium 

 has a flat, roughened surface, a tubular notched peristome, much indented round the 

 margin, one side often higher than the other, an eminence on the front of the zooecium 

 bearing an avicularium with a two-pointed beak and a mandible ending squarely, the 

 angles more or less pointed. There are larger avicularia at the forks of branches, having 

 wide, three-pointed mandibles, and there is an occasional small elongated avicularium on 

 the dorsal surface. Older colonies have the orifice much sunk, the rostrum, bearing an 

 avicularium, being level with the surface of the zooecium. There is a small broken piece of 

 a colony from Seychelles, which may not be the same species. It has more slender 

 branches, a small avicularium just below the lower margin of the orifice instead of the 

 large frontal one, while the large avicularium at the fork of the branches is divided into 

 four fingers. There are no ooecia on this species. 



Amirante, 15 — 35 fath. ; Seychelles, 34 fath. 



56. Schizoporella cecilii (Aud.). Hincks, Brit. Mar. Pol., p. 269. 

 Providence, 50—78 fath. 



57. Schizoporella triangula, Hincks, Ann. Mag. Nat. Hist., ser. 5, viii, 1881, p. 12. 



Providence, 50 — 78 fath. 



19—2 



