Zhen & Nicoll: Canning Basin Serratognathus bilobatus Fauna 
25 
Fig. 16. Tropodus australis (Serpagli, 1974). A,B, M element; (A), CPC39914, WCB705/243, posterior view (IY128-032); (B), CPC39915, 
WCB705/243, anterior view (IY129-007). (C), Sa element, CPC39916, WCB705/243, posterior view (IY128-034). (D), Sbl element (tri¬ 
costate), CPC39917, WCB705/243, outer lateral view (IY128-033). E,F, Sb2 element (four costate); (E), CPC39918, WCB705/243, outer 
lateral view (IY128-038); (E), CPC39919, WCB705/243, inner lateral view (IY128-036). G-7, Sc element; (G), CPC39920, WCB705/243, 
outer lateral view (IY129-003); (77), CPC39921, WCB705/243, inner lateral view (IY129-022); (7), CPC39922, WCB705/243, inner 
lateral view (IY118-032). J,K, Sd element, CPC39923, WCB705/243, (7), basal view (IY118-033), ( K ), basal view close up showing 
the lamellar structure in the basal cavity (IY118-034). L-N, Pa element; (L), CPC39924, WCB705/243, outer lateral view (IY128-028); 
(M), CPC39925, WCB705/243, inner lateral view (IY128-022); (AO, CPC39926, WCB705/243, inner lateral view (IY128-029). 0,P, Pb 
element, CPC39927, WCB705/243; (O), outer lateral view (IY129-031), (P), basal view (IY129-030). Scale bars 100 pm. 
Serratognathus diversus An, 1981 
Figs 12-14 
Serratognathus sp. A An et al., 1981: pi. 1, fig. 10. 
Serratognathus diversus An, 1981: 216, pi. 2, figs 23, 27, 
30; Zhen et al., in press a: figs 10A-K, 11A-K, 12D-M 
(cum syn.). 
Serratognathus obliquidens Chen, Chen & Zhang, 1983: 
136, pi. l,fig. 18. 
Serratognathus tangshanensis Chen, Chen & Zhang, 1983: 
136-137, pi. 1, figs 14-17; Chen & Zhang, 1989: 223, 
pl.5, fig. 12. 
Remarks. Both Serratognathus obliquidens and S. tangshan¬ 
ensis were erected as form species from the Honghuayuan 
Formation exposed in the Nanjing Hills (Chen et al., 1983). 
We consider them to be junior synonyms of S. diversus, 
representing the asymmetrical elements (Sb + Sc) of our 
current notation. 
Based on a large collection of S. diversus from the 
Honghuayuan Formation, Zhen et al. (in press a) recognized 
a trimembrate apparatus including symmetrical Sa, asym¬ 
metrical Sb and strongly asymmetrical Sc elements (Fig. 
12). Material of S. bilobatus from the Emanuel Formation 
shows the same apparatus. Morphologically, S. diversus 
and S. bilobatus are closely comparable except that the 
former has a much more prominent, laterally compressed 
cusp. Their elements are resembling a half-cut onion with 
a posteriorly located cusp enveloped anterolaterally by 
numerous overlapping laminar layers (varying from 6 to 20, 
see Fig. 13). The upper margins of these laminae are progres¬ 
sively lower anterolaterally. Laminae are ornamented with 
