BEITISH PAL^OGENE BRTOZOA. 253 



exceptionally well for D'Orbigny, and its claims cannot be so quietly set aside as Reuss 

 has done in the two lines in which he refers to it. Batopora is the better name, but 

 that is of course a mere matter of detail. 



Genus Obbitulipora, Stoliczka, 1862. 

 [Stoliczka, No. i, p. 90.] 

 Type species. 0. haidingeri, Stol. op. cit. p. 91, pi. iii. fig. 5. 



Diagnosis. A Celleporidan with a bilaminar zoarium composed of a flat round disk 

 supported laterally by a short stem. The zooecia of the disk are usually arranged 

 around a small central zocecium. The zooecia are holostomatous, with a large and 

 typically orbicular aperture. The ooecia are narrow, but globose and elevated. 

 Small avicularia and vibracula may or may not occur. 



Species 1. Obbitulipoea petioltjs (Lonsdale), 1850. 



Syn. Cellepora? petiolus, Lonsdale, 1850, Dixon, Geol. Suss. p. 151, pi. i. fig. 10; Morris, 1854, 

 Cat. Brit. Foss. ed. 2, p. 120; Mourlon, 1881, Geol. Belg. pp. 180, 191, 202; Vine, 

 1890, Proc. Yorks. Geol. & Polyt. Soc. xi. pp. 163, 164, pi. v. fig. 10 ; Reuss, 1867, Sitzb. 

 k. Ak. Wiss. Wien, Bd. Iv. Abth. 1, p. 217. 



Diagnosis. Zoarium : disks rather large for this genus ; thick at the margins and 

 depressed in the centre. The stem is short and, so far as known, unjoin ted ; when 

 broken away it leaves a large round scar. 



Zooecia numerous ; usually in fairly regular radial rows ; the apertures are orbicular 

 in the centre, but become elliptical at the margin ; those adjoining ooecia have the 

 margin nearest incurved owing to the overgrowth of the ooecium. Separated by inter- 

 spaces which are often marked by punctures. 



Ooecia very irre gularly distributed ; sometimes absent from the whole of one surface 

 of a disk, at others there are a few irregularly scattered, at others nearly every zooecium 

 has one. They are globose, but narrow. 



Distribution. Bracklesham Beds : Bracklesham, Bramshaw, Brook, Whitecliff Bay 

 (common). — Foreign. Belgium : Bruxellien, Laekenien, Wemmelien, and Tongrien. 



Type. Brit. Mus. 



Figures. PL XXXI. fig. 12. Zoarium, x4 diam. Fig. 12 a. Part of the same, 

 X 18 diam., to show the ooecia. Fig. 13. Another specimen, to show the stem. 

 Fig. 14. A young specimen in the Conescharellidan stage. 



Affinities of the Sjtecies. This species diflers from 0. haidingeri mainly by the fact 

 that the peripheral zooecia open upwards instead of outwards, a point well seen in a 

 comparison of Stoliczka's and Lonsdale's figures. 0. haidingeri is the nearest ally of 

 the English species ; if the two species should prove to be identical, Lonsdale's name 

 wiU have the prior claim to adoption. 



2o2 



