Ourikaia cf. calva Geyer 1990
This genus is characterized by a large and dominant glabella that is rounded in front and very convex. The palpebral lobe does not reach the posterior border furrow. The glabellar furrows are not as strongly pronounced as in Hamatolenus. The preglabellar field is narrow. This specimen shown below is particularly large measuring nearly 3 inches, and broad. Care must be taken not to mistake this more rare genus with H. Myopsolenus. There is some resemblance in terms of overall shape, but the Ourikaia has an unmistakably stout glabella and long and stout genal spines that the Myopsolenus lacks. Bottom photo shows the convexity of the glabella in comparison with the rest of the head.
The other important difference between this species and the Protolenines (Hamatolenus, Protolenus, Latoucheia) and Termierella is the position of the genal spines. The genal spines are longer and further distally from the pleural axes because the cephalon is wider.
Kenjiro 2012.6.14 (Edited 2019.11.17)