214 BRITISH AVONIAN CONODONT FAUNAS 
posterior extension of the carina are of equal elevation. The four high anterior 
denticles of the anterior blade give the anterior edge of the anterior blade a serrated 
appearance. The low carina is raised slightly above the level of the platform. 
The basal cavity is situated in the anterior part of the platform. It has an oval 
outline, with very thick lips. It is slightly longer than wide and a narrow trough 
runs from the pit to the posterior extremity of the platform. A keel runs from the 
anterior extremity of the basal cavity to the anterior extremity of the unit. 
Remarks. It is considered likely that Pseudopolygnathus postinodosus sp. nov. 
developed from Spathognathodus sp. nov. by the continued development of a platform, 
transitional specimens between the two species having been found. In these transi- 
tional specimens a second row of nodes is developed on the inner side of the blade, 
directly over the basal cavity. This development is in addition to the row of nodes 
on the outer side of the blade (see Fig. 47). 
Pseudopolygnathus primus Branson & Mehl 
Plate 6, figs. 4a—5c, 7I0a—I2c 
1934 Pseudopolygnathus prima Branson & Mehl: 208, Pl. 24, figs. 24, 25. 
1934 Pseudopolygnathus foliacea E. R. Branson : 316, Pl. 26, figs. 27, 28. 
1934 Pseudopolygnathus ivregularis E. R. Branson : 316, Pl. 26, figs. 25, 26. 
1934 Pseudopolygnathus corrugata E. R. Branson : 317, Pl. 26, fig. 23. 
1934 Pseudopolygnathus costata E. R. Branson : 317-318, Pl. 26, fig. 21. 
1934 Pseudopolygnathus distorta E. R. Branson : 318-319, Pl. 26, figs. 16, 17. 
21934 Pseudopolygnathus varicostata E. R. Branson : 318, Pl. 26, figs. 19, 20. 
1934 Pseudopolygnathus sulcifera E. R. Branson : 319, Pl. 26, fig. 15. 
1934 Pseudopolygnathus asymmetrica E. R. Branson : 320, Pl. 26, fig. 12. 
1934 Pseudopolygnathus inequicostata E. R. Branson : 321, Pl. 26, fig. 6. 
1934 Pseudopolygnathus crenulata E. R. Branson : 321, Pl. 26, figs. 4, 5, 7, 8. 
1934 Pseudopolygnathus lobata E. R. Branson : 322, Pl. 26, figs. 1, 2. 
1938 Pseudopolygnathus prima Branson & Mehl; Branson & Mehl: Pl. 33, figs. 47, 48. 
?1938 Pseudopolygnathus varicostata E. R. Branson ; Branson & Mehl: 133, Pl. 33, figs. 25, 
40. 
1939 Polygnathus subserrata Branson & Mehl ; Cooper: 404, Pl. 39, figs. 75, 76 only. 
1939 Pseudopolygnathus asymmetrica E. R. Branson ; Cooper : 406-407, Pl. 40, figs. 23, 24, 
59, 60, Pl. 41, figs. 13, 14. 
1939 Pseudopolygnathus crenulata E. R. Branson ; Cooper: 407, Pl. 40, figs. 25-27. 
21939 Pseudopolygnathus varicostata E. R. Branson ; Cooper: 408, Pl. 40, figs. 44, 45. 
1939 Pseudopolygnathus prima E. R. Branson & Mehl ; Cooper : 408, Pl. 40, figs. 30, 31. 
1939 Pseudopolygnathus ivregularis Branson ; Cooper : 408, Pl. 40, figs. 21, 22, 35, 36. 
1939 Pseudopolygnathus distorta E. R. Branson ; Cooper : 408-409, Pl. 40, figs. 49-50. 
1944 Pseudopolygnathus prima Branson & Mehl; Branson & Mehl: 244, Pl. 94, figs. 11, 12. 
1944 Pseudopolygnathus prima Branson & Mehl; Branson & Mehl: 181, Pl. 32, figs. 25, 26. 
?1944 Pseudopolygnathus varicostata E. R. Branson; Branson & Mehl: 181, 222, Pl. 32, 
figs. 25, 46. 
1949 Pseudopolygnathus aurita Youngquist & Patterson : 67-68, Pl. 16, figs. 5, 6. 
1949 Pseudopolygnathus cavinata Youngquist & Patterson : 68, Pl. 16, fig. 4. 
1949 Pseudopolygnathus ivvegularis Branson; Youngquist & Patterson: 68-69, Pl. 16, 
figs. I-3. 
1949 Pseudopolygnathus prima Branson & Mehl ; Thomas: 412, Pl. 4, fig. 17. 
