BRITISH AVONIAN CONODONT FAUNAS 89. 
DEscrIPTION. A clydagnathid with a high, equally tridenticulate anterior blade, 
a short posterior blade, and a heavy asymmetrical basal cavity. 
The unit is arched and triangular in cross-section. The blade is short and high, 
consisting of three equal denticles fused into a blade but with free tips which are 
slightly divergent. The platform is lanceolate, nearly four times as long as wide, 
and is ornamented with two rows of denticles along the platform margins, separated 
by a straight, shallow, smooth trough. The denticles tend to be transversely 
elongate. The posterior part of the platform possesses a short carina, of about three 
nodes, which is produced posteriorly to give a short posterior blade. 
In lateral view the platform posterior to the basal cavity is deflected continuously 
downwards through 30°, and its depth decreases markedly towards the posterior. 
The basal cavity is large, ovate, nearly symmetrical and is confined to the anterior 
part of the platform ; it flares slightly in lateral view. 
Remarks. This clydagnathid is similar to C. davensis, but the blade is much 
higher, has fewer denticles and the deflected posterior platform is unique. The 
cavity is also different in that all other clydagnathids have an obviously asymmetrical 
cavity, whereas this form possesses a nearly symmetrical cavity. 
Genus EUPRIONIODINA Ulrich & Bassler 1926 
1925 Euprvioniodina Bassler: 219. (nom. nud.) 
1925 Synpyviontodina Bassler: 219. (nom. nud.) 
1926 Euprioz:: :2 Ulrich & Bassler: 29. 
1926 Synprioniodina Ulrich & Bassler: 42. 
TYPE SPECIES. Evuprioniodina deflecta Ulrich and Bassler 1926. 
DEscrRIPTION. This genus is characterized by its general pick-shape, with a short, 
denticulated, highly compressed anticusp. The posterior limb is long and bears 
numerous erect denticles. 
Apical denticle 
Anterior bar Bee, 
Posterior bar 
Outer lateral face 
Aboral margin 
Fic. 21. Euprioniodina sp. showing morphological terms used in the text. 
