ALDI^'GA AND THE RIVER-MtlRRAT CLIFFS, SOUTH AUSTRALIA. 305 



rounded on the distal edge, becoming wider on the proximal, which is 

 slightly concave 0-14:-0'l 7 millim. wide. In the recent and fossil spe- 

 cimens there are at the two sides of the aperture small teeth, one on 

 each side directed downwards towards the neural wall. The shape 

 of the operculum indicates the presence of such teeth, but they have 

 been overlooked. The dorsal surface much resembles that of C. 

 biradiata, W., and this species, C. albirostris, C. pertusa, and C. tri- 

 denticulata, are no doubt allied. 



The specimen that I referred to pro tern, as 0. repleta (Journ. 

 Roy. Micr. Soc. vol. ii. p. 392, pi. xv. figs. 6, 8), is C. albirostris, 

 and grows round the stalks of seaweed, rising into ridges with 

 zooecia on each face of the ridge. These have no oral spines, fre- 

 quently the rostrum bifurcates, and ovicells surmounted with small 

 avicularia are supported by the rostrum. Smitt refers to the 

 Floridan specimens sometimes having two spines and sometimes 

 being without ; and as this is made a leading distinction between 

 C. albirostris and C. hastigera, I should certainly feel inclined to 

 unite them, for in each colony of Q. albirostris there is great varia- 

 tion in the size and form of the rostral process. 



We see in this species and C. tridenticulata how little importance 

 we should attach to the mode of growth ; and among specimens 

 picked up at the same time near the Semaphore, Adelaide, as being 

 the same species, we have found that although they most closely 

 resembled one another in general appearance, they represent ^efero- 

 pora crevicornis, d'Orb., Gellepora albirostris, and C. tridenticulata. 



Log. Living : Florida, 25-35 fathm. ; Sydney (Sm.) ; Heard 

 Islands, 75 fathm. (B.); Semaphore, Adelaide (A. W. W. coll.). 

 Fossil : Eiver-Murray Cliffs. 



65. Cellepora pertusa, Smitt. 



Discopora pertusa, Smitt, Floridan Bryozoa, p. 72, pi. xii. figs. 

 240, 241. 



A specimen from Aldinga is irregularly subglobular ; diameter 4 

 to 7 millim. In the shape of the zocecia and of the large oral aper- 

 tures it corresponds with the Floridan specimens ; but in the fossil 

 there are no avicularia, and from Smitt's figures the avicularia only 

 seem to occur on some of the zooecia. Oral aperture 0*28 millim. 



Log. Florida, 35-60 fathm. 



66. Cellepora pertusa, Sm., var. ligulata. 



The zoarium consists of hollow cylindrical branches. The zooecia 

 are ovate, elongate, irregular, with a rounded aperture nearly 

 straight below and slightly contracted at the sides ; there is a very 

 minute avicularium below or to the side of the aperture, and besides 

 this there are frequently small ligulate or spatulate avicularia on 

 the zooecia, and here and there an elongate spatulate vicarious 

 avicularium. The oral aperture is 0-12 millim. 



I feel much doubt about any determination of this form, but in 

 calling it a variety of pertusa the similarity in most points is indi- 



