92 Mr. A. W. Waters on 
round primary is surrounded by five zocecia, and then from 
these the ordinary zoccia grow, so that there are zocecia all 
round the primary, and I have already suggested that the 
first zocecium of Batopora was not very far from the pit, 
formerly mistaken for a ‘“ primordial cell.” The section, 
text-fig. 2, c, was made to show the central zoccia at right 
angles to text-fig. 2, 6, and the relationship of the zocecia on 
each side. Text-fig. 2, c, is magnified about twice as much 
as text-fig, 2, 6, and is from about the line a-a, text-fig. 2, «. 
A series of transverse sections are required to completely 
understand the growth, but this is not possible. 
There is in O. petiolus a pit to the younger zoaria, and as 
growth proceeds this is prolonged, so that in mature zoaria 
there is a tunnel from the centre to the large external pit, 
and this can in places be seen through the layers of zocecia 
covering it. Sections show this tube more clearly from the 
centre to the projection, and inside this tube fairly large 
pores occur in regular lines. 
Some of the specimens in the British Museum, marked 
Heteropora glandiformis, Gregory *, are young O. petiolus, 
and in one case a pit can be seen. Besides this there are one 
or two which, though worn, show signs of a base like that 
of Conescharellina canceliata, Busk (figure 22 ina paper now 
ready). The specimens, being mounted, could consequeutly 
not be examined all round, but in none was I able to 
distinguish Cyclostomatous characters. 
Reuss thought that the process of petiolus, subsequently 
called stalk, pedicle, or pit, had no connection with the 
structure of the zoarium, and was, only accidental, but we 
now see that it is the prolongation of the pit. 
O. petiolus, Lonsd., occurs from beds of about the same age 
as the Mazzurega deposit, having been found by Dixon from 
Bracklesham, by Stoliczka from Latdorf, by Reuss from 
the Lower Oligocene of Calbe and Biinde ; Vine says from 
Barton Bay ; Brackelsham ; Stubbington; Gregory besides 
these mentions Bramshaw and Brook; Vincent and Th. 
Lefevre + say it occurs in Belgium from the Bruxellian, 
Laekenien (Upper Eocene), Wemmelien and Tongrian (Oligo- 
cene), subsequently also referred to by Mourlon; Canu 
mentions it from the Bartonian of Var in the Paris basin. 
Loc. of excentrica. Tortonian (Seg.), Mioc. of Calabria 
* “British Paleogene Bryozoa,” Trans. Zool. Soc. vol. xiii. p. 261, 
pl. xxxii. fig. 11 (1893). 
+ “Vaune Laek. sup. des Environs de Bruxelles,” Ann. Soc. Malae. de 
Belge, vol. vii. p. 29 (1872). 
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