Examples of Pseudoniscus from the Upper Silurian-aged (Ludlow) Vernon Shale, New York State, USA. A, B, Pseudoniscus clarkei (NSYM 19113), without any evidence for a lateral compound eye (LCE). A, complete specimen. B, close-up of box in C, showing well-defined ophthalmic ridge (white arrow). C, D, Pseudoniscus roosevelti (NYSM 19112) displaying a reniform LCE preserved on the left side of the prosomal shield. C, complete specimen. D, close-up of box in C. Note dark pigmentation of eye and ommatidia (black arrows). Photograph credit: A, B, Lisa Amati; C, D, Russell Bicknell.