106 BRITISH AVONIAN CONODONT FAUNAS 
1959 Gnathodus punctatus (Cooper) Voges : 283-284, Pl. 33, figs. 34-37. 
1960 Gnathodus punctatus (Cooper) Kronberg, Pilger, Scherp & Ziegler : Pl. 4, figs. 15-18. 
1963 Gnathodus punctatus (Cooper) Ziegler : Pl. 2, fig. 4. 
MATERIAL. 13 specimens : figured, X 131, X132, X 133. 
RANGE. Avon Gorge Samples Z 33-38. 
DESCRIPTION. This species is characterized by the adult specimens having the 
nodes of the inner and outer sides of the platform fused with those of the carina in the 
posterior two thirds of the platform. The pattern of nodes on the platform is also 
characteristic, there being four rows, radiating from the junction of the platform and 
blade. The platform is asymmetrical, being widest at the anterior end and pointed 
at the posterior ; the outer side is wider than the inner. In juvenile examples the 
carina is high, but in adult specimens the carina is fused with a row of nodes on the 
inner and outer sides of the platform. A double row of nodes is present on the outer 
side in fairly juvenile examples, but frequently there is only one row of nodes 
developed on the inner side in juveniles. The blade is slightly longer than the 
platform. 
REMARKS. Hass (1959) has illustrated growth stages of this species. The 
specimens obtained in the present study most closely resemble those figured by Hass 
in Pl. 47, figs. 12, 13. Typically, the smaller inner side of the platform bears one 
node, whereas the wider outer side of the platform has a few scattered nodes. The 
outer side of the platform extends to the posterior tip of the unit. The inner side of 
the platform does not extend to the posterior tip of the unit, but extends further to 
the anterior than does the outer side of the platform. 
In North America Gnathodus punctatus is abundant in the middle faunal zone of 
the Chappel Limestone, and also occurs in the Siphonodella cooperi and Bactro- 
gnathus communis zone. In the Avon Gorge it is characteristic of the Zz beds. 
Gnathodus semiglaber Bischoff 
Plate 30, fig. 1 
1947 Gnathodus perplexus (Branson & Mehl) Mehl & Thomas: to, PI. 1, fig. 4. 
1957 Gnathodus bilineatus semiglaber Bischoff : 22, Pl. 3, figs. 1a, b, 2-10, 12-14. 
1957 Gnathodus bilineatus semiglaber Bischoff ; Ziegler in Fliigel & Zeigler: p. 38, l. p11, 
figs. 5, 8, 14, 19 only (non pl. 111, fig. 23 =Gnathodus punctatus, Pl. IV, fig. 11, non PI. 3, 
fig. 22=Gnathodus girtyi simplex Dunn). 
1959 Gnathodus semiglabey Bischoff ; Voges: 285, Pl. 33, figs. 38, 39. 
1960 Gnathodus semiglaber (Bischoff) Ziegler in Kronberg, Pilger, Scherp & Ziegler: PI. 4, 
figs. 3-6. 
1962 Gnathodus semiglabey (Bischoff) Collinson, Rexroad & Scott : 10, 22, Chart 3. 
1962 Gnathodus semiglaber (Bischoff) Higgins: 13, Pl. 3, fig. 26. 
1962 Gnathodus semiglaber (Bischoff) Miller : 1388, fig. 1. 
1962 Gnathodus semiglaber (Bischoff) Meischner : 31, text-fig. 1o. 
1964 Gnathodus semiglaber (Bischoff) Rexroad & Scott: 30, Pl. 2, figs. 1, 2. 
MATERIAL. 3 Specimens : figured, X 421. 
RANGE. Avon Gorge Z 28-Z 30. 
