JURASSIC BRYOZOANS FROM BALTOW, POLAND 
97 
igs 19-22 Jurassic bereniciform cyclostomes with transversely-ridged colonies similar to Hyporosopora baltovensis sp. nov. 19-20, Hyporosopora 
enstonensis (Pitt & Thomas, 1969), BMNH D51451, holotype, Bathonian, Hampen Marly Beds, Enstone, Oxfordshire, England; 19, x 13; 20, 
gonozooid, x 80. 21-22, Plagioecia rugosa (d’ Orbigny, 1853), BMNH BZ51, Lower Kimmeridgian, St Jean des Sables, near La Rochelle, Charente 
Maritime, France; 21, small colony with prominent transverse ridges, x 14; 22, gonozooid in a larger colony encrusting the same substrate, x 30. 
981), H. enstonensis (Pitt & Thomas, 1969) from the Bathonian of 
xfordshire (Figs 19-20), and Mesenteripora undulata (Michelin, 
845) from the Bathonian of Normandy (revised by Walter, 1970). A 
ew post-Jurassic cyclostomes also possess transversely ridged colo- 
ies (e.g. Plagioecia plicata (Canu) from the Eocene of France, see 
uge, 1979a; Berenicea undata Canu & Bassler, 1920 from Eocene 
f the USA), but this morphology seems to be proportionally less 
ommon than in the Jurassic. 
Compared with Hyporosopora baltovensis, the gonozooid in 
lagioecia rugosa is broader and is penetrated by autozooidal 
pertures (Fig. 22). In other respects, however, the two species are 
ery similar, although the transverse ridges tend to be more strongly 
eveloped in P. rugosa (Fig. 21). Walter (1970: 218) considered P. 
ugosa to be a junior synonym of Cellepora orbiculata Goldfuss, 
826 from the Oxfordian of Streitburg in Germany. The syntypes 
Universitat Bonn, Goldfuss Collection 104) of C. orbiculata have 
been studied but are poorly-preserved, lack diagnostic gonozooids, 
and probably represent more than one species. C. orbiculata is 
probably better discarded. 
Hyporosopora portlandica has narrower gonozooids than H. 
baltovensis, and autozooidal apertures which are more widely- 
spaced and frequently transversely elongate. Multilamellar growth, 
rarely seen in H. baltovensis, is very common in H. portlandica, 
resulting from either spiral overgrowth or eruptive budding of 
subcolonies onto the colony surface. (Note that the considerable 
discrepancy in autozooidal size between the holotype of H. 
portlandica and many other specimens previously assigned to this 
species, for example by Taylor (1981), suggests that more than one 
species may be present). 
Gonozooid morphology is similar in H. enstonensis and H. 
baltovensis, but the former species has smaller autozooids and more 
prominent transverse ridges (Figs 19-20). M. undulata has consid- 
