BRITISH AVONIAN CONODONT FAUNAS 191 
TYPE LOCALITY AND HORIZON. North Crop. Sample ZLA 32. 
RANGE. North Crop ZLA 29-ZLA 33, Avon Gorge Z 33-C 9. 
DEscRIPTION. The free blade and outer platform are closely similar to P. lacinatus 
s.s., but there is modification of the inner posterior platform margin. The postero- 
inner portion tends to be produced as a lobe, narrowing rapidly to the posterior 
termination, which is formed by a posterior projection of the carina, to give a short 
posterior anterior blade. The anterior inner platform tends to be considerably 
upturned and the platform edge is very close to the anterior blade. In aboral view 
the unit exhibits the characteristics of P. lacinatus s.s. 
Remarks. The narrowing of the anterior portion of the platform and the lobation 
of the posterior inner platform give this subspecies the aspect of Siphonodella, but the 
basal cavity precludes the inclusion of these forms in this genus. 
Polygnathus lobatus lobatus Branson & Mehl 
Plate 9g, figs. 5a—8c 
1938 Polygnathus lobata Branson & Mehl: 146, Pl. 34, figs. 44-47. 
1939 Polygnathus lobata Branson & Mehl ; Cooper: 4o1, Pl. 39, figs. 29, 30. 
1939 Polygnathus curta Cooper (partim) : 400, Pl. 39, figs. 37, 38 only. 
1949 Polygnathus lobata Branson & Mehl ; Thomas: 411, 418, Pl. 3, fig. 11. 
1949 Polygnathus cunulae Youngquist & Patterson : 62, Pl. 15, figs. 11-15. 
1951 Polygnathus inoynata Branson & Mehl; Youngquist & Downs: 787, Pl. 111, fig. 11 
(non Pl. 111, figs. 17, 18 = P. inornata inornata). 
1957 LPolygnathus lobata Branson & Mehl ; Bischoff: 42, Pl. 2, fig. 19. 
1964 Polygnathus lobata Branson & Mehl ; Rexroad & Scott : 35, Pl. 2, figs. 15, 16. 
MATERIAL. 21 specimens : figured, X 376, X 377, X 378, X 440. 
Rance. North Crop KL 16-KL 20. 
DEscrRIPTION. This unit is boat-shaped, with a curved axis. The platform is flat 
in the posterior portion but deepens to form two troughs either side of the carina in 
the anterior portion. The unit tends to be symmetrical in the anterior half, but in 
the posterior, the outer platform wall flares out to give a lobate process. The plat- 
form then narrows rapidly to give a pointed posterior termination. The ornament 
consists of transverse ridges dying out towards the carina and terminating on the 
platform edges as low nodes or short chevron-shaped denticles. The carina is 
sinuous, consisting of low nodes which merge with the free blade, which is itself short 
and high, being highest at its mid point. 
In aboral view the unit is keeled, there being a small cavity posterior to the junc- 
tion of the free blade with the platform. The antero-lateral corners project as two 
“horns ”’ in aboral view. The whole central part of the aboral surface tends to be 
more or less flat and unornamented, except for the sinuous median ridge. The outer 
margin of this flattened chine-like area is sharp, and the flat sloping faces of the outer 
aboral edges join it at a sharp angle. The surface of the chine is finely striate, with 
the striations more or less parallel to the outer margins. In at least some specimens 
