Fig. 8 Leioclema sp. A. NHM PD 8307; longitudinal section, x22. 
Figs 9-10 Leioclema sp. A. 9, NHM PD 8308; transverse section, x22. 10, NHM PD 8307; tangential section, showing petaloid autozooecia, x101. 
Fig. 11 Leioclema sp. B., NHM PD 8306; 11a, longitudinal section, x86; 11b, transverse section, x55; 11c, tangential section, x86. 
Figs 12, 13 Leioclema? sp. 12, NHM PD 8138; longitudinal section, x22. 13, NHM PD 8137; 13a, tangential section, x30; 13b, tangential section, showing 
large acanthostyles indenting autozooecial walls, x112. 
Fig. 14 Hallopora peculiaris Pushkin (in Ropot & Pushkin, 1987). NHM PD 8396; longitudinal section, x22. 
Fig. 15 Hallopora atf. wesenberginia (Dybowski, 1877), NHM PD 8312; 15a, longitudinal section, x22; 15b, tangential section, x37. 
Limestones (middle Ordovician) of Kentucky which are very similar 
to those from Minnesota and Iowa. Restudy is needed to assess the 
variability within the species, and it is possible that the Estonian and 
American forms are different species. 
Until further material can be examined, this one incomplete 
specimen is left in open nomenclature. 
C. BUTTLER 
Genus HETEROTRYPA Nicholson, 1879 
Heterotrypa sp. Fig. 7 
MATERIAL. NHM PD 8314. 
DESCRIPTION. Zoarium erect with thin cylindrical branches, on 
average 4 mm in diameter. 
