BRITISH AVONIAN CONODONT FAUNAS 211 
DESCRIPTION. The unit is straight, the platform being about twice as long as the 
blade. It is widest near mid-length and tapers to the posterior. The central carina 
is nodose and is continued a short distance beyond the posterior edge. One of the 
nodes of the carina near the posterior is higher than the others. The platform is 
ornamented by a number of short ridges near the outer margin, normal to the 
carina. The troughs between the carina and the ridges are unornamented. The 
anterior blade is high and composed of 5 fused denticles. In lateral view this species 
has a characteristic outline. The oral edge is highest at the anterior and slopes 
regularly to the posterior. The oral edge of the platform is arched convexly. The 
aboral edge is strongly concavely arched. In aboral view there is a very large pit 
and a strong keel. 
Remarks. The present specimens, although very close to P. longiposticus, differ 
in the outline of the platform, which more closely resembles that of Polygnathus 
macrus Cooper and Polygnathus orthus Cooper. 
Pseudopolygnathus multistriatus Mehl & Thomas 
Plate 5, figs. 14-16. Plate 6, fig. 2 
1947 Pseudopolygnathus multistriata Mehl & Thomas: 16, Pl. 1, fig. 36. 
1947 Pseudopolygnathus attenuata Mehl & Thomas: 17, Pl. 1, fig. 9. 
1947 Pseudopolygnathus rustica Mehl & Thomas: 17, Pl. 1, fig. 8. 
1947 Pseudopolygnathus striata Mehl & Thomas: 17, Pl. 1, fig. ro. 
1957 Pseudopolygnathus multistriata Mehl & Thomas ; Bischoff: 51, Pl. 4, figs. 33, 35. 
1959 Pseudopolygnathus lanceolata Hass : 391, Pl. 47, figs. 16-26. 
1964 Pseudopolygnathus multistriata Mehl & Thomas; Rexroad & Scott: 41, 42, Pl. 2, 
fig. 30. 
MATERIAL. 46 specimens : figured, X 485, X 486, X 487, X 484. 
RANGE. Avon Gorge Z 23-Z 29. 
DESCRIPTION. This species is distinguished by the platform, which is not 
markedly asymmetrical ; it is ornamented by transverse ridges, usually nine or more 
on either side of the central carina. There is a short anterior blade, and a trough on 
the side of the carina in the anterior part of the left side of the platform. Adult 
specimens frequently have rough oral surfaces owing to the coarse nature of the 
ornament. 
The platform is three and a half times as long as wide and has convex margins. 
The axis is straight to slightly curved and the platform on the left side of the carina 
does not extend as far to the anterior, as does the platform on the right side. The 
platform on either side of the carina is ornamented by g nodes which elongate into 
ridges reaching the carina. A slight trace of a trough is, however, present in the 
anterior part of the left side of the platform. The anterior two thirds of the carina 
is composed of fused denticles, but in the posterior third the denticles of the carina 
are free and distinct. The carina is continued a short distance beyond the posterior 
extremity of the platform. The anterior blade, composed usually of 5 denticles, is 
highest at the anterior and decreases in height to its junction with the carina. The 
