208 BRITISH AVONIAN CONODONT FAUNAS 
in synonomy may explain the different stratigraphic ranges in North America and 
Germany for the two species in question. 
Pseudopolygnathus dentilineatus E. R. Branson 
Plate 5, figs. ga-13c. Plate 6, figs. 8a—c 
1934 Pseudopolygnathus dentilineata E. R. Branson : 317, Pl. 26, fig. 22. 
21934 Pseudopolygnathus varicostata E. R. Branson : 318, Pl. 26, figs. 19, 20. 
1934 Pseudopolygnathus subrugosa E. R. Branson : 318, Pl. 26, fig. 18. 
1934 Pseudopolygnathus projecta E. R. Branson : 320, Pl. 26, figs. ro, 11. 
1934 Pseudopolygnathus brevimarginata E. R. Branson : 319, Pl. 26, fig. 3. 
21939 ©Pseudopolygnathus varicostata E. R. Branson ; Cooper : 408-409, Pl. 40, figs. 44-45. 
21956 Pseudopolygnathus striata Mehl & Thomas ; Bischoff & Ziegler : 164, Pl. 11, fig. 20. 
non 1957 Pseudopolygnathus dentilineata E. R. Branson ; Bischoff : 50, 51, Pl. 4, figs. 30-32, 
( = Pseudopolygnathus vogesi sp. nov.) (Pl. 4, fig. 29 = Pseudopolygnathus primus) 
non 1959 Pseudopolygnathus dentilineata E. R. Branson ; Voges : 300-301, Pl. 34, figs. 49, 
50, text-fig. 5 Il = Pseudopolygnathus vogesi sp. nov. 
non 1962 Pseudopolygnathus dentilineata E. R. Branson ; Ziegler: Pl. 2, figs. 10, 11. 
MATERIAL. 182 specimens : figured, X 478, X 479, X 480, X 481, X 438, X 477. 
RANGE. Avon Gorge Z 12-Z 28. 
DEscRIPTION. This species is represented by pseudopolygnathids with an 
asymmetrical platform. Both the right and the left sides of the platform are 
ornamented with 4 to 7 nodes or ridges which are confined to the margin of the 
platform. The basal cavity is a symmetrical element, with a fold on the inner 
margin and a smooth convex outer margin in both right and left forms. The basal 
cavity, as pointed out by Klapper (1966 : 15), is as wide as the platform in aboral 
view. 
This species has bilaterally asymmetrical right and left forms. The platform is 
two and a half times as long as wide, being widest at the anterior and narrowing to 
the pointed posterior. In adult specimens the platform is less triangular and more 
oval in outline. The margin of the right side of the platform in both right and left 
forms is convex and widest at mid-length : that of the left side of the platform is 
widest close to the anterior and narrows to the pointed posterior. The right side of 
the platform in both right and left forms extends further to the anterior than does the 
left side. The platform on either side of the carina is ornamented by 4 to 7 nodes or 
ridges, which are confined to the margin. There is usually one more node present on 
the right side of the platform than on the left. In smaller specimens a distinct 
trough may be present between the denticles of the margin and the carina, in the 
anterior half of the left side of the platform. A central straight to slightly curved 
nodose carina runs the length of the platform. The nodes of the anterior portion of 
the carina are stubby and wider than those of the posterior, which are more distinct 
and erect. The carina in smaller specimens extends a short distance beyond the 
posterior extremity of the platform. 
The anterior blade, commonly composed of 6 denticles, is highest at the anterior 
end and slopes uniformly to the posterior. 
