02 Mr. A. W. Waters on 



round primary is surrounded by live zooccia, and then from 

 tliesi^ tlie ordinary zooecia grow, so that there are zooecia all 

 round the primary, and I have ah'eady suggested that the 

 first zoo'cium of Batopora was not very far from the pit, 

 formerly mistaken lor a " primordial cell/^ The section, 

 text-tig. 2, c, Avas made to sliow the central zooccia at right 

 angles to text-fig. 2, b, and the relationship of the zoceeia on 

 e.ieh side. Text-fig. 2, c, is magnified about twice as much 

 as text-fig. 2, h, and is from about the line a-a, text-fig. 2, (t. 

 A series of transverse sections are required to completely 

 un lerstand the growtli, but this is not possible. 



There is in 0. petiohis a pit to the younger zoaria, and as 

 growth proceeds this is prolonged, so that in mature zoaria 

 tliere is a tunnel from the centre to the large external pit, 

 and this can in places be seen through the layers of zooecia 

 covering it. Sections show this tube more clearly from the 

 centre to the projection, and inside this tube fairly laige 

 pores occur in regular lines. 



Some of the specimens in the British Museum, marked 

 Heteropora fflandiformis, Gregory'^, are young O, petiuius, 

 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 cuncellata, Busk (figure 22 in a paper now 

 leady). The specimens, being mounted, could consequently 

 not be examined all round, but in none was I able to 

 distinguish Cyclustomatous characters. 



lleuss thought that the process of petiohis, subseqnentl}'^ 

 culled stalk, pedicle, or pit, had no connection with the 

 stiueture of the zoarium, and was only accidental, but Ave 

 now sre that it is the prolongation of the pit. 



O. petiolus, Lonsd., occurs from beiJs of about the same age 

 as the JNIazzurega deposit, having been found by Dixon from 

 iiracklesham, by Stoliczka from Latdorf, by Jieuss from 

 the Lower Oligoeene of Calbe and Biinde ; Vine says from 

 ilarton Hay ; Braekelsham ; Stubbington; Gregory besides 

 these mentions Bramshaw and Brook; Vincent and Th. 

 IjL'fevref say it occurs in Belgium from the Bruxellian, 

 Laekeuien (Upper Eocene), Wemmelien and Tongrian (Oligo- 

 eene), subsequently aiso referred to by Mourlon ; Canu 

 mentions it from the Bartonian of Var in the Paris basin. 



Loc. of excentrica. Tortouian {Seg.), Mioc. of Calabria 



* " I'ritisli Palaeogene Bryozoa," Trans. Zool. Soc. vol. xiii. p. 201, 

 pi. xxxii. lig. 11 (1893). 



t " Fiiuue Ijaek. sup. des Euviious de Biuxelles,'' Ann. Soc. .Malac. de 

 13elge, Vol. vii. p. 29 (^1j>72j. 



