40 PROCEEDIlsrGS OF THE NATIONAL MUSEUM vol.76 



1887. Cellepora tridentieulata Waters, On Tertiary Bryozoa from New Zealand, 



Quarterly Journal Geological Society, vol. 43, p. 68. 

 1890. Cellepora tridenticulata Kirkpatrick, Hydroida and Polyzoa, Torres 



Straits, Scientific Proceedings, Royal Dublin Society, vol. 6, p. 612. 

 1895. Cellepora tridenticulata MacGillvray, A monograph of Tertiary Polyzoa 



of Victoria, Transactions of the Royal Society of Victoria, p. 107, pi. 14, 



figs. 4^6. 



MeasureTnents. — 



(7wt= 0.14-0.16 mm. 

 Apertura j ^^=o 16-0 20 mm Diameter of tubes, 0.30 mm. 



Variations. — The species of the tridenticulata group are quite 

 variable and easy to confuse among themselves. The published fig- 

 ures of Holoporella tridenticulata are incomplete, and it is rather 

 difficult to get an exact idea of the species. Fortunately, the pub- 

 lished determinations having been made by actual comparison of 

 specimens, the bibliography is exact. 



The apertural width is 0.16-0.20 mm. measured on the same large 

 zoarium. It is about 0.16 mm, on fossil specimens from the Bal- 

 combian of Muddy Creek, Australia, and on the recent examples of 

 Busk, 1884, while the one from Australia (Waters, 1885) shows 0.20 

 mm. The aperture is always transverse. 



The lyrule and the two cardelles are very resistant, rather large,, 

 sometimes bifurcated. They disappear only by mutilation after 

 death. Even on the fossils they persist sufficiently to permit deter- 

 mination. Our specimens did not have oral spines. There are two 

 on Busk's figure, 1884, and two to four on those of MacGillivray, 

 1886 ; they are often lacking on the fossils from Australia. 



The surface of the cell is smooth. It is granular as figured by 

 Busk, 1884, and MacGillivray, 1886, but on the fossils from Australia 

 it is smooth or granular. The areolar pores are large, rare, and very 

 irregularly distributed. They are more numerous and more regular 

 on the fossils from Australia. There are none on the recent speci- 

 mens figured by Busk and by MacGillivray. There is not a single 

 interzooecial avicularium. Waters, 1885, said that 'they were very 

 rare. Busk, 1884, found and figured the mandible on a recent speci- 

 men from Australia. On our fossils from Australia they were very 

 numerous and never elliptical. Although variable, they are generally 

 long, narrow, a little constricted in the middle of their length. 



Sporadically, between the zooecia, long cylindric tubes spring forth 

 on which there is neither operculum nor denticles. This is the first 

 time that they have been figured. Busk, 1884, noted them thus: 

 "Another curious feature is the frequent occurrence on the surface 

 of the zoarium of long tubular processes or tunnels, looking like enor- 

 mously elongated zooecia. The nature of these appendages appears 

 very obscure." MacGillivray (1886 and 1895) did not rediscover 

 them on his specimens recent or fossil. They are observed only on 



