94 Mr. A. W. Waters on Australian Bryozoa. 



with a median rib, and on each side of this an irregular area. 

 On each side below the ovicell two thick club-shaped spines. 



The ovicell is composed of two calcareous layers, the under 

 one smooth, so that when the upper one is removed no trace 

 of the area is shown. The structure of the ovicell in Flustra 

 episcopalis is just the same, and no doubt the two species are 

 allied ; but in F. episcopalis, B., the operculum is entire, 

 whereas in the present species it is of the Membraniporidan 

 type. There is a thick tubular growth down the side of the 

 zoarium of episcopalis. 



On account of the prominent spines I call this militaris, in 

 opposition to the less-armed F. episcopalis. 



Mr. Hincks defines Flustra as with the ovicells immersed ; 

 but in the two species considered they are much raised. 



Log. Port Jackson (New South Wales) . 



24. Diachoris spinigera, MacG. 



DiacJwris s/)m?^«'a, MacGillivray, Trans. Roy. Soc. Vict. 1859, vol. iii. 

 p. 165, pi. ii. fig. 12 ; Zool. Vict. dec. v. p. 32, pi. xhi. fig. 3. 



The specimen from Shoalhaven Bay has the zooecia sub- 

 erect ; the spines are mostly towards the distal end, often only 

 two or three on each side ; on one side only an avicularium 

 with a prominent beak. There is considerable irregularity in 

 the number of spines, and from this specimen I consider that 

 D. distans, Hincks, is too closely allied to be separated as a 

 species. 



Log. Wilson's Promontory ; Portland (Victoria) ; Shoal- 

 haven Bay, 8 fath. (New South Wales). 



EXPLANATION OF PLATE IV. 



Fiff. 1. Menipea cervicornis, MacG., var., X 25. 



Fig. 2. Flustra ijiilitaris, sp. nov., X 16. 



Fiff. 3. Bugula neritina (L.), with avicularia. From Ball's Head, x 16. 



Fig. 4. Sketch of Caberea lata (p. 84), showing chitinous tubes at the 

 junction, X 12. 



Fig. 5. Micropora ratuniensis, sp. nov., X 16. 



Fig. 6. CeUaria gracilis (B.), showing continuous calcareous wall before 

 the articulation is formed. The chitinous tubes are just com- 

 mencing. X 25. From Holborn Island. 



Fig. 7. Sketch of Canda arachnoides, Lamx., showing chitinous tubes at 

 the articulation. X 25. 



Fig. 8. Meinhranipm-a Savartii, And. ?, X 16. From Darnley Island. 



Fig. 9. Operculum of Catenicella alata, W. Thorns., X 85. 



Fig. 10. Operculum of Catenicella hastata, B., X 85. 



Fig. 11. Operculum of Catenicella delicatula (Wilson), X 85, 



Fiq. 12. Operculum of Catenicella Buskii, W. Thoms., X 85. 



Fig. 13. Operculum of Catenicella ventricosa, B., X 85. 



