192 BRITISH AVONIAN CONODONT FAUNAS 
(e.g. Pl. 9, fig. 6a—c, X 376), the aboral cavity is situated about a quarter of the total 
length of the platform from the anterior end. 
ReMARKS. This form is distinguished from P. inornatus s.s. by possessing a lobe 
on the outer margin. The two subspecies appear to be transitional. 
Polygnathus lobatus inflexus subsp. nov. 
Plate 9, figs. ga—c 
DERIVATION OF NAME. From the inflexing of the inner platform margin. 
Diacnosis. P. lobatus in which inner anterior lateral margin is more or less 
strongly inflexed. 
MATERIAL. 4 specimens : Holotype X 375 (figured). 
TYPE LOCALITY AND HORIZON. North Crop. Sample KLM 1. 
RANGE. North Crop KL 16-KL 20, Avon Gorge K 12. 
DESCRIPTION. Ina few specimens whose general characteristics are similar to P. 
lobatus lobatus, there is a marked tendency for the inflexing and upraising of the inner 
anterior lateral margin of the platform. This tends to be confined to the anterior 
third or half of the platform. The oral edge bears a series of irregular, low, rounded, 
confluent denticles, giving a bluntly serrate margin. It stands conspicuously higher 
than the carina and rather higher than the opposing outer lateral margin. It reaches 
almost the height of the large denticles in the median portion of the anterior blade, 
and it runs broadly sub-parallel to the line of the anterior portion of the carina. It is 
at the posterior end of this inflexed portion that the carina tends to be more or less 
strongly laterally deflected. 
REMARKS. This form appears to be undergoing similar adaptations to those of 
P. inornatus rostratus within the species P. inornatus. This may imply either close 
relationships between P. lobatus and P. inornatus or independent (functional?) 
convergence. 
Polygnathus sp. 
Plate 15, figs. ga—c 
MATERIAL. I specimen : figured, X 531. 
RANGE. Farlow Sample FAR 4A. 
DeEscRIPTION. This specimen seems to be a pathological individual of the genus 
Polygnathus. It is distinguished by a lip-like secondary development on the inner 
lateral platform, so that although the anterior edge of the platform forms a typical, 
open, spout-like development on the inner lateral side and the inner anterior lateral 
margin, it is strongly developed and upturned. It ceases after running for about a 
quarter of the total length of the platform, and the platform itself is then bent 
outwards, as though some injury had taken place to the individual and then been 
reformed. The rather low sinuous margin of the platform gives a wide platform for 
