306 A. W. WATERS ON CHILOSTOMATOUS BRYOZOA TROM 



cated, but the minuteness of the aperture and the avicularia on the 

 front of the zocBcia distinguish it. 

 Log. Eiver-Murray Cliffs. 



67. Cellepora biradiata, sp. noY. (PI. YII. figs. 11, 12.) 



In a specimen from the River-Murray Cliffs the zoarium is conical, 

 mamillated, in diameter about 20 millim., and has the general 

 appearance of a large Lunulites. The zoarium is formed by many 

 superposed layers of zooecia. On the dorsal surface there are 

 radiating lines, and when the outer surface is broken away, the 

 walls of a double row of zooecia are seen, and each such double 

 row is separated from its neighbours by septa (fig. 11). 



Zooecia irregular, subglobular, raised, with the oral aperture 

 rounded on the distal edge, nearly straight on the proximal, forming 

 more than a semicircle, 0*12 millim. wide. Below the aperture, 

 a little to one side, is a small raised avicularium, with the mandibular 

 opening forming a nearly equilateral triangle. In one specimen 

 there are two spatulate avicularia, and sometimes three rudimentary 

 teeth can be distinguished in the oral aperture ; but this is excep- 

 tional. Ovicells subglobose, broader than high, smooth, resembling 

 the ovicells of Cellepora ramidosa, L., as figured by Hincks, Brit. 

 Mar. Polyzoa, pi. lii. fig. 8. 



This and C. compressa, Busk, C. tridenticulata. B., and C. alhi- 

 rostris, Sm., all seem closely related. 



68. Cellepora tridenticulata. Busk. 



Cellepora tridenticulata, Busk, Journ. Linn. Soc. vol. xv. p. 347 ; 

 * Challenger ' Report on the Polyzoa, p. 198, pi. xxix. fig. 3, 

 pi. xxxv. fig. 17. 



Prom the River-Murray Cliffs there is a solid dome-shaped colony 

 formed of many layers, measuring about 25 millim. in diameter, and 

 in a colony from Aldinga the zoarium commenced in a dome shape, 

 then spread out to about 10 centim. in diameter and grew into a 

 solid mass 10 centim. high. The zooecia are irregular, immersed, 

 with the oral aperture straight below, rounded at the distal end, 

 forming a little more than half a circle, and a little way down the 

 aperture on the proximal edge there are three narrow teeth directed 

 forwards. Below the oral aperture there is a small rounded avicu- 

 larium, and there was a spine on each side of the aperture. Oral 

 aperture about 0*2 millim., from which it can be seen that in the 

 fossil it was larger than in the specimen described by Mr. Busk ; but 

 recent specimens from the Semaphore, Adelaide, correspond with the 

 fossil. On the under surface the elongate hexagonal shape of each 

 cell is visible, and there are projections for attachment. Out of 

 several fossil specimens I have only found two with a vicarious avi- 

 cularium (onyehocellarium), and in this case it was spatulate, as 

 figured by Mr. Busk. In recent specimens sometimes the avicularium 

 is very small, at others it rises into a large rostral process, and occasion- 

 ally there are four teeth in the oral aperture. C. tridenticulata and 

 C. honolidensis, B., are very closely allied. 



