"Delaware Mountain formation, Guadalupe Point, Guadalupe Mountains, Texas (station 2931?). Delaware Mountain formation, southern Delaware Mountains, Texas (station 2969)." [Girty, 1908: 429.]
"Shell small, strongly oblique. Posterior ear depressed, moderately wide, prolonged, pointed, defined in outline by a deep sinus. Umbonal slope subangular, slightly curved, addressed to the cardinal line at an angle of about 45 degrees. Body of the shell narrow, strongly produced backward, limited in front by an angular rib nearly perpendicular to the hinge line, and abruptly raised on the anterior side by reason of a depressed area which it surves partially to define. The depressed area continues anteriorly for hearly half of a quadrant, when there is another abrupt elevation directed at about 45 degrees to the hinge, the remaining portion of the anterior end being well rounded.
Surface where well preserved marked by more or less irregular, closely arranged, squamose concentric lirae." [Girty, 1908: 427.]
Girty, 1908: pl. 29, fig. 14.