BRITISH AVONIAN CONODONT FAUNAS 189 
Rance. North Crop ZLA 29-ZLA 33. Avon Gorge Z 33-C 20. 
DEscRIPTION. The anterior blade and the anterior portion of the platform are 
exactly comparable with P. Jacinatus s.s., but the posterior part of the inner platform 
is reduced and does not extend to the posterior termination, the carina being 
extended posteriorly as a short posterior free blade. 
Polygnathus lacinatus circaperipherus subsp. nov. 
Plate 11, figs. 12a—-15c 
DERIVATION OF NAME. From the platform edge, which encircles the posterior 
portion of the platform. 
Diacnosis. P. lacinatus with platform margin complete around posterior part of 
platform ; posterior section of carina obsolescent. 
MATERIAL. 32 specimens : Holotype X 364, Paratypes X 365, X 366, X 367 
(all figured). 
TYPE LOCALITY AND HORIZON. North Crop. Sample ZLA 32. 
RANGE. North Crop ZLA 17-ZLA 30, Avon Gorge C 7. 
DESCRIPTION. This subspecies is very similar to P. lacinatus except for the 
posterior platform termination. The platform edge is wrapped around the posterior, 
the carina dying away before it reaches the posterior. In aboral view the keel is also 
terminated abruptly and the whole posterior of the unit is rounded off. The 
posterior outline may be expanded and club-like (e.g. Pl. 11, fig. 12b) to bluntly 
pointed (e.g. Pl. 11, fig. 15a). There is some variation in the form of the basal 
cavity. In some specimens it is extended relatively further posteriorly than in 
others. In neither case, however, is there an ungrooved posterior keel developed 
behind it. 
REMARKS. This morphological variation is also seen in our faunas in the species 
of P. communis. 
Polygnathus lacinatus lacinatus Huddle 
Plate 11, figs. 8a—roc 
1934 Polygnathus lacinata Huddle: 95, Pl. 8, figs. 1-3. 
1939 Polygnathus lacinata Huddle ; Cooper: 4o1, Pl. 40, figs. 3, 4. 
1949 Polygnathus sagittavria Youngquist & Patterson : 66, Pl. 15, figs. 9, ro. 
1950 Polygnathus aff. Polygnathus sagittaria Youngquist & Patterson ; Youngquist, Miller & 
Downs : 527, Pl. 67, figs. 2-4. 
1951 Polygnathus sagittaria Youngquist & Patterson ; Youngquist & Downs: 788, Pl. 111, 
figs. 7-9. 
1959 Polygnathus inornata E. R. Branson; Voges: 291, Pl. 34, figs. 17-20 (non Pl. 34, 
figs. 12-16 = P. inornata). 
MATERIAL. 753 specimens : figured, X 368, X 369, X 370. 
RANGE. North Crop ZLA 29-ZL 19, Avon Gorge Z 32-C 20. 
